diff --git a/src/persistence/db/upgrades/dbto11.cpp b/src/persistence/db/upgrades/dbto11.cpp
index 5f14c601c6..43829d48e5 100644
--- a/src/persistence/db/upgrades/dbto11.cpp
+++ b/src/persistence/db/upgrades/dbto11.cpp
@@ -20,10 +20,52 @@
 #include "dbto11.h"
 
 #include "src/core/toxpk.h"
+#include "src/persistence/db/upgrades/dbupgrader.h"
 
 #include <QDebug>
 
 bool DbTo11::dbSchema10to11(RawDatabase& db)
+{
+    QVector<RawDatabase::Query> upgradeQueries;
+    if (!appendDeduplicatePeersQueries(db, upgradeQueries)) {
+        return false;
+    }
+    if (!db.execNow(upgradeQueries)) {
+        return false;
+    }
+    upgradeQueries.clear();
+
+    if (!appendSplitPeersQueries(db, upgradeQueries)) {
+        return false;
+    }
+    upgradeQueries += RawDatabase::Query(QStringLiteral("PRAGMA user_version = 11;"));
+    bool transactionPass = db.execNow(upgradeQueries);
+    if (transactionPass) {
+        return db.execNow("VACUUM");
+    }
+    return transactionPass;
+}
+
+bool DbTo11::appendDeduplicatePeersQueries(RawDatabase& db, QVector<RawDatabase::Query>& upgradeQueries)
+{
+    std::vector<DbUpgrader::BadEntry> badPeers;
+    if (!getInvalidPeers(db, badPeers)) {
+        return false;
+    }
+    DbUpgrader::mergeDuplicatePeers(upgradeQueries, db, badPeers);
+    return true;
+}
+
+bool DbTo11::getInvalidPeers(RawDatabase& db, std::vector<DbUpgrader::BadEntry>& badPeers)
+{
+    return db.execNow(
+        RawDatabase::Query("SELECT id, public_key FROM peers WHERE CAST(public_key AS BLOB) != CAST(UPPER(public_key) AS BLOB)",
+                           [&](const QVector<QVariant>& row) {
+                               badPeers.emplace_back(DbUpgrader::BadEntry{row[0].toInt(), row[1].toString()});
+                           }));
+}
+
+bool DbTo11::appendSplitPeersQueries(RawDatabase& db, QVector<RawDatabase::Query>& upgradeQueries)
 {
     // splitting peers table into separate chat and authors table.
     // peers had a dual-meaning of each friend having their own chat, but also each peer
@@ -32,7 +74,6 @@ bool DbTo11::dbSchema10to11(RawDatabase& db)
     // since each group is a chat so is in peers, but authors no messages, and each group
     // member is an author so is in peers, but has no chat.
     // Splitting peers makes the relation much clearer and the tables have a single meaning.
-    QVector<RawDatabase::Query> upgradeQueries;
     if (!PeersToAuthors::appendPeersToAuthorsQueries(db, upgradeQueries)) {
         return false;
     }
@@ -40,12 +81,7 @@ bool DbTo11::dbSchema10to11(RawDatabase& db)
         return false;
     }
     appendDropPeersQueries(upgradeQueries);
-    upgradeQueries += RawDatabase::Query(QStringLiteral("PRAGMA user_version = 11;"));
-    bool transactionPass = db.execNow(upgradeQueries);
-    if (transactionPass) {
-        return db.execNow("VACUUM");
-    }
-    return transactionPass;
+    return true;
 }
 
 bool DbTo11::PeersToAuthors::appendPeersToAuthorsQueries(RawDatabase& db, QVector<RawDatabase::Query>& upgradeQueries)
diff --git a/src/persistence/db/upgrades/dbto11.h b/src/persistence/db/upgrades/dbto11.h
index 4ac66df99c..71ad583d1a 100644
--- a/src/persistence/db/upgrades/dbto11.h
+++ b/src/persistence/db/upgrades/dbto11.h
@@ -20,6 +20,7 @@
 #pragma once
 
 #include "src/persistence/db/rawdatabase.h"
+#include "src/persistence/db/upgrades/dbupgrader.h"
 
 #include <QVector>
 
@@ -28,6 +29,11 @@ class ToxPk;
 namespace DbTo11
 {
     bool dbSchema10to11(RawDatabase& db);
+    bool appendDeduplicatePeersQueries(RawDatabase& db, QVector<RawDatabase::Query>& upgradeQueries);
+    bool getInvalidPeers(RawDatabase& db, std::vector<DbUpgrader::BadEntry>& badPeers);
+    bool appendSplitPeersQueries(RawDatabase& db, QVector<RawDatabase::Query>& upgradeQueries);
+
+
 namespace PeersToAuthors
 {
     bool appendPeersToAuthorsQueries(RawDatabase& db, QVector<RawDatabase::Query>& upgradeQueries);
diff --git a/test/persistence/dbupgrade/dbTo11_test.cpp b/test/persistence/dbupgrade/dbTo11_test.cpp
index c758ffc093..ae6d2c2ab7 100644
--- a/test/persistence/dbupgrade/dbTo11_test.cpp
+++ b/test/persistence/dbupgrade/dbTo11_test.cpp
@@ -30,7 +30,7 @@
 namespace
 {
 const auto selfPk = ToxPk{QByteArray(32, 0)};
-const auto aPk = ToxPk{QByteArray(32, 1)};
+const auto aPk = ToxPk{QByteArray(32, '=')};
 const auto bPk = ToxPk{QByteArray(32, 2)};
 const auto cPk = ToxPk{QByteArray(32, 3)};
 const auto selfName = QStringLiteral("Self");
@@ -38,13 +38,15 @@ const auto aName = QStringLiteral("Alice");
 const auto bName = QStringLiteral("Bob");
 const auto selfAliasId = 1;
 const auto aPeerId = 2;
-const auto aChatId = 1;
+const auto aPeerDuplicateId = 5;
+const auto aChatId = 3;
 const auto aAliasId = 2;
+const auto aAliasDuplicateId = 4;
 const auto bPeerId = 3;
-const auto bChatId = 2;
+const auto bChatId = 1;
 const auto bAliasId = 3;
 const auto cPeerId = 4;
-const auto cChatId = 3;
+const auto cChatId = 2;
 
 void appendAddPeersQueries(QVector<RawDatabase::Query>& setupQueries)
 {
@@ -60,6 +62,9 @@ void appendAddPeersQueries(QVector<RawDatabase::Query>& setupQueries)
     setupQueries.append(RawDatabase::Query{QStringLiteral(
         "INSERT INTO peers (id, public_key) VALUES (4, ?)"),
         {cPk.toString().toUtf8()}});
+    setupQueries.append(RawDatabase::Query{QStringLiteral(
+        "INSERT INTO peers (id, public_key) VALUES (5, ?)"),
+        {aPk.toString().toLower().toUtf8()}});
 }
 
 void appendVerifyChatsQueries(QVector<RawDatabase::Query>& verifyQueries)
@@ -113,6 +118,9 @@ void appendAddAliasesQueries(QVector<RawDatabase::Query>& setupQueries)
     setupQueries.append(RawDatabase::Query{QStringLiteral(
         "INSERT INTO aliases (id, owner, display_name) VALUES (3, 3, ?)"),
         {bName.toUtf8()}});
+    setupQueries.append(RawDatabase::Query{QStringLiteral(
+        "INSERT INTO aliases (id, owner, display_name) VALUES (4, 5, ?)"),
+        {aName.toUtf8()}});
 }
 
 void appendVerifyAliasesQueries(QVector<RawDatabase::Query>& verifyQueries)
@@ -146,11 +154,11 @@ void appendAddAChatMessagesQueries(QVector<RawDatabase::Query>& setupQueries)
     setupQueries.append(RawDatabase::Query{QStringLiteral(
         "INSERT INTO history (id, message_type, timestamp, chat_id) VALUES (2, 'T', 0, '%1')").arg(aPeerId)});
     setupQueries.append(RawDatabase::Query{QStringLiteral(
-        "INSERT INTO text_messages (id, message_type, sender_alias, message) VALUES (2, 'T', '%1', ?)").arg(aAliasId),
+        "INSERT INTO text_messages (id, message_type, sender_alias, message) VALUES (2, 'T', '%1', ?)").arg(aAliasDuplicateId),
         {QStringLiteral("Message 2 from A to Self").toUtf8()}});
 
     setupQueries.append(RawDatabase::Query{QStringLiteral(
-        "INSERT INTO history (id, message_type, timestamp, chat_id) VALUES (10, 'F', 0, '%1')").arg(aPeerId)});
+        "INSERT INTO history (id, message_type, timestamp, chat_id) VALUES (10, 'F', 0, '%1')").arg(aPeerDuplicateId)});
     setupQueries.append(RawDatabase::Query{QStringLiteral(
         "INSERT INTO file_transfers (id, message_type, sender_alias, file_restart_id, "
         "file_name, file_path, file_hash, file_size, direction, file_state) "