what would happen if two SV promoter show in one vector - (Oct/20/2005 )

Dear fella,
I am going to insert the whole cassete of blasticidin including SV promoter, blasticidin DNA and poly A and without cleave off the neomycin cassette also include a SV promoter and polyA. what would happen?

by the way, there is a bit of f1 original was gong to insert into the second vector. what effect will be?
Thanks

Kind of difficult to tell what would happen here. In the worst case scenerio, there might be interference between the two promoters competing for transcription factors. My hunch is that this should work fine.