Quick theory here:
Starrk's beyond Resurrection form has 2 hollow holes, one being his own and one being in the place that matches Lilynette's own hollow hole on her abdomen.
Now, what if Starrk's initial release mode ALREADY gave him 2 hollow holes? But we just couldn't see it because he had a double-breasted vest on, covering his abdomen..
I mean, it would make sense though because the beyond Resurrection forms are just an enhanced version of their normal Resurrections, she did fuse back with him to become "one" and why would a hogyoku fusion give him an extra hollow hole?
Not saying he does have one in his initial release, just something to think about ;)
Either way, I love these new forms and I can't wait to see Harribel's and Barragan's!
I also like how they used a penis like appendage for Szayel's Hogyoku placement haha that was smart xD