Typically a Grand Jury is impaneled for only a specific period. Generally 90 days.
The GJ will then meet only once a week and then only if the Prosecutor has a case for them to review.
Only on rare occasions is a special GJ empanelled for a specific case that will be seated long term.
Judges are reluctant to seat a special GD because it is a great imposition on peoples time and it is difficult for people to remain impartial on such cases today because of all of the news coverage of such a case.
A prosecutor could certainly take the same case to a GJ more than once. If more than one prosecutor worked the case it certainly could have gone before different GJs.
ok, I have a memory, tho, of a former co-worker who’d been called for jury duty that evolved into being asked to serve on a Grand Jury and she was to serve on it for 18 months which about drove her over the edge.