My wife likes DPs and she's had her fair share, it's extremely difficult to co-ordinate cuming at the same time, the guy that's usually in her ass comes first due to the immense sensation of her tight asshole almost milking whomevers cock is in her ass.
She usually let's her DP playmates come at their own pace, whom ever cums first usually soaks and lingers In which ever hole they in at the time of cuming whilst the other guy gets to finish when he's ready wherever he wants.
In general she loves hot cum in her ass, and I have also seen her ask the pussy partner to switch to her ass once the inicial ass partner is done and have both partners cum in her ass one after another.