Whenever I play a record while an in game track is playing, in survival mode, creative mode, in the overworld, Nether and End, the in game music will play over the jukebox music. This has been a problem ever since the new sound system was implemented and I thought it was going to be fixed, but after all these versions this bug still exists. I recently put in C418- Wait in a jukebox on a SMP Vanilla multiplayer server and the jukebox music started playing (server side) but then my client's in game music (client side) started playing overlapping this and causing an undesired effect. I know friends who have experienced this issue too and I personally have experienced it on many different systems across many different minecraft versions after the new sound system was implemented