As with most things in life, the devil is in the details
Having a speaker with multiple woofers mounted in a front baffle (very common) and in phase should pose no additional phase issues (in and of itself and driver to driver), unlike a port. So it's not the number of sources, it's the location of such sources and the phase of each source.
The problem with ports is that while they extend bass to lower frequencies, if you want to integrate a sub(s) you now have to contend with the main woofer(s) and now a port OOP with the speaker itself often at the back of the speaker further exacerbating the issue. The best solution is the original employed by M&K (I think) which was the first sub / sat system designed to roll off the sats, roll in the sub(s) and have very minimum frequency overlap. That's what the JLA CR1 does.
In my setup with side firing woofers and side firing ports right behind the woofers, I have the ports plugged up making integration much easier and sonically better. If my room was 2x the Cu ft, I'd probably leave them unplugged. Companies like B&W (I believe) and Kef even provide foam to plug the ports should one chose to.