Fix multitrack movie recording

BizHawk.Client.Common/movie/bk2/Bk2Movie.cs

@@ -88,6 +88,10 @@ namespace BizHawk.Client.Common
 		}
 
 		public virtual void Truncate(int frame)
+		{
+			// This is a bad way to do multitrack logic, pass the info in instead of going to the global
+			// and it is weird for Truncte to possibly not truncate
+			if (!Global.MovieSession.MultiTrack.IsActive)
 			{
 				if (frame < _log.Count)
 				{
@@ -95,6 +99,7 @@ namespace BizHawk.Client.Common
 					Changes = true;
 				}
 			}
+		}
 
 		public IController GetInputState(int frame)
 		{