Welcome to the Q&A Forum

I'd agree with Sanket on (1) - while, not a huge fan of creating new URLs for near duplicates (there may be some other ways, like dynamically modifying the content), canonical tags are definitely your best bet here if you need those unique URLs. I'll add a caveat on (2), though. Sometimes, canonical tags can "stick" a bit longer than you'd like, and Google may not re-index quickly. Adding a self-referential canonical tag does seem to help, anecdotally. What I'd also do is put those URLs back in your XML sitemap once they're unique (I'd leave them out while they're duplicates) - that can spur Google to reindex, and the self-referential tag can tell them to cancel the previous directive. Otherwise, they sometimes act like the old canonical is still in place.