I used to live in DC for a couple of years.
Orthodox parishes are great there! Those, which provide (2) liturgies per Sunday are:
-St. Catherine's Greek Orthodox Church, Falls Church, VA - GOA
-St. Nicholas Orthodox Cathedral, Washington, DC - OCA
-St. John the Baptist Russian Orthodox Cathedral, Wahington, DC - ROCOR.
At of these, and numebr of others are multi-ethnic. So, languages at services were different. I know for sure that at St. Nicholas, they place a moveable altar table in front of a main altar for the earlier liturgy. I do strongly believe that is the case for other (2) parishes as well. All these churches change Antiminsions for the liturgies. In fact, St. John the baptist has really many Antminsions. At all these parishes, different clergy celebrate these liturgies.
At all UOC-USA parishes, where (2) liturgies transpire, different clergy celebrate those.
On a different note, several years ago I have read in a Polish Orthodox calendar that some Orthodox priest in Poland has a parish and a mission, which was already preparing to the construction of the chruch at that time. However, that mission did not have an assigned priest. So, this priest was driving to the misssion and serving another Liturgy every Sunday. I am not sure if that common in Poland, or that was a real exception. In any case, as long as Canons provide at least any opportunity of doing so in certain cases, I believe that Polish Autocephalous Church, which actually strengthens and grows, made a very valuable decision here.