Sorry to laugh - but my girls STILL do that to each other - (minus the ripping up stuff) they DO however get the toys squeaking till they break it....but it's pretty normal sounding to me - I think even if Dreama has her own toys - she'll still like Wosies better ...
My girls both usually pick a favorite only if the OTHER one is playing with it first....
HAVE FUN ! Yorkies are natural Thieves and just love to steal off each other....wait till they start hiding the toys so the other can't play - that's always a fun game