Much to my surprise, both Spring 2018 sections of CS/ECE 374 are now full (except for a handful of seats reserved for current students who may need to retake the class), with a total enrollment of 580 students. That makes nest semester's 374 the largest upper-division (≥300) course in the CS department's, if not the College of Engineering's, history. (I'm not willing to speculate about the campus.)
It is unclear at this point whether expanding to admit even more students is possible. There are seats available in ECEB 1002 (where I'm teaching Section A), but there may not be enough qualified TAs and CAs to support even bigger enrollment. I'm not willing to let more students in without sufficient qualified course staff to support them.
I might run my own waiting list, or at least my own survey of unmet demand. But a waiting list only makes sense if the number of additional students is small, and if the list has a short expiration date. I am not willing to force dozens of extra students to submit coursework for weeks or months with no guarantee that they will eventually get in (like we did in Fall 2016). That would just create extra stress for the students, for the course staff, for the academic office, and for me.
I expect both sections to remain full until the semester begins; after that, transfers become dangerous. Mahesh and I plan to run our sections completely independently, with (slightly) different topical coverage/emphasis, and with distinct lab and homework problems. Any student who transfered from one secction to the other in the middle of the semester would not get credit for the work they did in the old section, and might miss material previously covered in the new section.
If you are registered for lecture section AL1, you must also register for one of the AY* lab sections. If you are registered for lecture section BL1, you must also register for one of the BY* lab sections. We expect most lab sections to fill up, so (at least for the first few weeks) you should attend only your officially registered lab section. And you should attend the labs designed for the topics (and homework) in your section.
If you are registered for a lab section that does not correspond to your lecture section, contact the CS or ECE academic office as soon as possible.
If by "work" you mean "study", then yes, of course. (Don't forget to cite your sources!) But if by "work" you mean "submit joint homework", then no. The two sections will have distinct homeworks. Even if we coincidentally assign the same problem in the same week, homework teams must come from the same lecture section.