User account become missing after migrate another user account to target domain

hi folks,

Good day. This issue recently happened in our project and after a session with quest support, we manage to find the root cause. SR number is 4983080. since its already remark as close, i choose to ask here instead of open a new ticket. 

Mmad tools identify the matching SIDhistory attribute and causing a merge of two different accounts (User A and User B). User A migrated to target domain long before and User B is actually new user in source domain.

i was looking into using Conflict Resolution Rules. to avoid same issue occur again for new batch of user migration. Is this the correct as preventive measurement? as i read is it will affect both migration and sync jobs. In this scenario, we actually have 1-way sync target to source. 

If i apply this rule, should it not giving any impact to users in target domain? or causing user account to lockout?