a Hulk 2on1?
Thanos best chances here is via early BFR's to them both....else eventually loses as both Hulks are easily capable of surpassing his strength levels...as well as surviving his levels of punishment.
Thanos likely gets the living hell beat out of him for as long as his endurance and self-sustainance lasts..which would be a very very long fight.
The thing about fighting Thanos though, is he really doesnt go down by physical means either. I think we would see Thanos kick the crap out of both early on for a good while - but unless they are BFR'd....which he is capable of - they keep coming and win over time.
On terms of pure fighting ability...Thanos is nastier and more proficient than them both, and would not hold back with cosmic levels of assaults early on....which I actually still think has good chances of BFRs.
But if not, both Hulks would continue fighting and continue to rise in attack power throughout the fight....inevitably beating Thanos into submission.