2 musics in same time?

Hello,
what is the good way when LT play 2 musics in same time ?

I have had this problem after a slot change and it’s not very cool for listeners …

I’ve done " systemctl restart libretime-playout " (and after it was ok)

So, i would like to know if it’s the best to do or if there is another way without music cut …;

Thanks in advance

Patrick