If Eren Jaeger dies without transfering his titan powers, will both powers transfer to the same child?
I think Yes.  According to the manga, if the host of the titan body dies, their power goes to the newly born child.
And since Eren has now acquired more than one titan's powers, then if Eren dies, then each of his powers will go to separate newly born children.
Here is a fandom theory if you would like to read... that can answer much of your questionsfandom theory
Warning : there might be some spoilers in the link, read only if you have read till current manga chapter