Happens all the time as each application is processed individually. Unless its a case wher one is delayed by more than a day or two. Do not know about parent's processed first, the case of
@Anncs (Visa) appeared to be one such where the delay looked odd -- but child's application was delayed.
For OCI, there were many cases, but none unresolved in a day I think.
EDIT: mistakenly posted to visa thread first