Yes the -wl1 "upgrades" the existing power kernel (meaning it removes it then installed -wl1 kernel) so if you want both you need to do some workarounds like that. I don't think there's any point in having both installed, but if you want to do it there's no technical reason why it won't work.

Also beware that the modules for each kernel use up a lot of rootfs, so be careful not to run out of space.