To my knowledge those offerings are not doubled again during such an event.

So you get your score say 20k bp and those offering double it. However the 2x bp doesn't get applied to that now 40k it just doubles the base score and gives another 20k for a total of 60k.

Hope that's clear as I'm tired.

Now that being said I still save my bloody streamers for events because its awesome when you get up to 5 played and the killer farms.

But extra feels bad when you and 3 friends each play one and the killer brings a mori

So while its fun to get those huge payouts during double bp it makes no difference if you use them now or during an event.

As to when the next one may be I'm not sure maybe during the summer event possibly.