I was hoping someone can help me understand an issue I am seeing with the Mediaplayer class. 

I am creating a music app that needs to play two music files at the same time. In one of the use case scenarios I want to be able to play an MP3 track and then initiate another MP3 to start playing at a differnt volume over the top of the first. 

I have found that the Android mediaplayer class offers this functionality and have created a test application to do this by simply creating two instances of mediaplayer. 

For example...

```
MediaPlayer mMediaPlayer1,mMediaPlayer2;

mMediaPlayer1 = new MediaPlayer();
mMediaPlayer2= new MediaPlayer();

```

The problem I am having is that in the emulator it works fine and on most devices I try it works fine but on a few test devices I get odd results when I try to start the second mediaplayer/track. 

What happens is that the volume of either the second or the first audio track suddenly reduces to nothing. I can see that the mediaplayer is still "playing" as I have several progress bars setup to track its progress but you can't hear anything. 

I've seen this on both a OnePlus One and a OnePlus X phone. On my Asus Tablet and a Smasung A3 phone it works fine though. Its not related to the OS version either as I've tried it on 4.4.2, 5, 6 and 7 with mixed results. It definitly seems to be hardware related. 

I've also seen related posts describing this issue but none so far with an answer as to what is causing it. 

Can anyone explain this or shed any light on the problem? Even if it is only to understand the limitation of what I am doing?

FYI - I did look at Soundpool but can't use it becuase the clips I am using are bigger than 1Mb.

Thanks in advance...