merge mapping issue - It's still not clear how the merging issue gets resolved in test complete

It's still not clear how the merging of the name mapping gets resolved? Whenever we merge we get a conflict message with no mechanism to resolve. 

when we tried to merge one file into another its just show attached message. we wanted to know does the merge deletes the existing mere if it found same as in target file?

seems that what i have experienced. its strange for me when i merge two name mapping files but after merging object not founded !

please can i have a robust solution on this issue?

Please find attached.