Pipe collision detected - how to merge tables?

Hello, I have problem with pipe collision detected with bird.. i would like to have separate routing table for tranzit bgp peers and another table for internet exchange peers, but i need merge routes from this two tables to master table.. but there is problem with Pipe collision detected, because there is a lot of the same routes from both tables. Is there any way how to merge tables with aware of localpref or something like this? Maybe protocol preference? Regards, Dan