Since a member is supposed to only receive one BOGO per membership year, and they last 9 months, it is technically impossible for one to have more than one BOGO to use even on such a long stay. Of course, we all know of ways of getting more than one, and if one is an RA it is quite conceivable that an existing Ambassador member will be referred and get an RA kit with another BOGO within the 9-month period thus having two valid BOGOs. Or if you are travelling with your partner, they might have their own BOGO and are letting you use it.

However, aside from the "legality" of having two BOGOs, it should be possible as long as the ten nights cover the required days. Let's say you check in on a Thursday, pay for that night and Friday, so the Saturday would be free with the first BOGO. You then pay for Sunday, Monday, Tuesday, Wednesday, Thursday and Friday, and use the second BOGO for the second Saturday. (Or arrive on Friday or Saturday...etc., etc.)

Just one further aside, given you only earn 2K for the entire 10-night stay, plus any elite and other promotional bonuses, have you thought of breaking your stay in two, albeit you'd need to spend a night at a local HI or CP, then return. This could certainly increase your yield in points, particularly with the 2nd stay bonuses? Or are you staying with your partner? If so, break the booking into three parts, booking the first few nights of the stay in your name and using the first BOGO, then book a night or two in their name (set up a PC account for them, then transfer the points into your account, then book the balance of the nights and the second BOGO weekend in your own name. Of course, you will have to officially check in and out and change rooms a couple of times, but this would certainly max out the PC points.