From f31220c1ee7aaf3f559b73248961d79208a089d8 Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Fri, 14 Feb 2020 19:56:01 +0900
Subject: [PATCH] Fix exception when adding duplicate items

---
 .../Visual/Multiplayer/TestSceneMatchSongSelect.cs        | 8 ++++++++
 osu.Game/Screens/Select/MatchSongSelect.cs                | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/osu.Game.Tests/Visual/Multiplayer/TestSceneMatchSongSelect.cs b/osu.Game.Tests/Visual/Multiplayer/TestSceneMatchSongSelect.cs
index 434b265f9c..5820da811d 100644
--- a/osu.Game.Tests/Visual/Multiplayer/TestSceneMatchSongSelect.cs
+++ b/osu.Game.Tests/Visual/Multiplayer/TestSceneMatchSongSelect.cs
@@ -126,6 +126,14 @@ namespace osu.Game.Tests.Visual.Multiplayer
             AddAssert("playlist has 1 item", () => Room.Playlist.Count == 1);
         }
 
+        [Test]
+        public void TestAddSameItemMultipleTimes()
+        {
+            AddStep("create new item", () => songSelect.BeatmapDetails.CreateNewItem());
+            AddStep("create new item", () => songSelect.BeatmapDetails.CreateNewItem());
+            AddAssert("playlist has 2 items", () => Room.Playlist.Count == 2);
+        }
+
         private class TestMatchSongSelect : MatchSongSelect
         {
             public new MatchBeatmapDetailArea BeatmapDetails => (MatchBeatmapDetailArea)base.BeatmapDetails;
diff --git a/osu.Game/Screens/Select/MatchSongSelect.cs b/osu.Game/Screens/Select/MatchSongSelect.cs
index 4edc968e8a..cb0d09b6bb 100644
--- a/osu.Game/Screens/Select/MatchSongSelect.cs
+++ b/osu.Game/Screens/Select/MatchSongSelect.cs
@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using System.Linq;
 using Humanizer;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -53,6 +54,7 @@ namespace osu.Game.Screens.Select
         {
             PlaylistItem item = new PlaylistItem
             {
+                ID = (Playlist.LastOrDefault()?.ID + 1) ?? 0,
                 Beatmap = { Value = Beatmap.Value.BeatmapInfo },
                 Ruleset = { Value = Ruleset.Value }
             };