I just upgraded to endntoe x9 and when inserting a tempoary citation ({parker, 1997@218}) the page number is repeated [(Parker, 1997, p. 218218)]. It does that same with any additional information (suffix).
I haven’t been able to recreate this issue, but I only have the [expired] trial version of X9 on my Mac. Considering no-one has responded with a solution for the other post, I’d suggest getting in touch with tech support.