Hi Elena -
I've tried to reproduce this error in a new, simpler WPF project, but merge appears to work in all of the smaller projects I've made. However the behavior is still incorrect in our larger project. I've installed Test Studio on a different machine and the behavior is even different here than on the originally observed machine. I'm not able to share this project here in the forums (I'll open a support ticket with it however), but attached are two screen shots showing the currently observed behavior where there are 2 elements with the same name (before the element name was similar, but not the same).