Like I said before, what your hearing in the during 00:53-00:56, and 1:43-1:45 is all single bass. Rob is hitting the bass on the upbeat rather than the downbeat. Like think of it this way. count to 4 but go 1and2and3and4and (For simplicity purposes). Rob is hitting between the number and the and. Like as his snare hit starts to come up the bass hits half-way between the beat and the next snare hit. This makes it seem like he is hitting during the snare hit as well, just because how heavy he is hitting the snare and how heavy the music is behind him. Like I said ALOT of punk/hardcore/metalcore bands use it if they don't have a double bass. LP has dabbled into hitting on the upbeat on In Pieces. That entire guitar line is hit on the upbeat, which is a huge characteristic of Ska music.
During 00:27-00:29 That might be sampled drums like I said, but again sounds like the bass drum in alot of the other songs on the album. If Rob did actually play that, it can be played using a single. the Double just makes it easier, since playing 8th notes at that speed with a single bass actually takes a tole on your leg haha, plus there are quads and triplets, sometimes back to back which is possible but extremely difficult.