Your best bet, if it plays something you really really like, in a RT, is to freeze that track and or export it before you do any sort of regeneration.

You can also regenerate that same RT multiple times and save each one in a DAW or in Real Band.

I find that BiaB is the one that recreates the tracks when you change something. When I work in RB, the tracks I generate are fixed and don't change with every regen. I regenerate only if I don't like the track in RB. ANd like I said, I will sometimes generate 3 to 5 instances of the same track. They are all different as you have observed.

I, and others use this to create parts in songs. The piano fills and the guitar solo in THE BEST CHRISTMAS on my music page were done this exact way. 3 pianos and 5 guitars from the same track/style mixed and edited in a DAW.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.