I don’t know if you “can’t” per se but it’s not recommended and highly uncommon. has it been done, sure, but it’s very much the minority.
if it were me I wouldn’t unless I knew each charging source was smart and could monitor/adjust based on voltage/current since each charging source would never be identical.
to break it down further, and more simplistically, multiple charging sources in itself is not uncommon on a single battery bank. On my last RV solar setup I had shore power (inverter charging), solar, and alternator (dc-dc charger) all tied to a single bus bar. There would be no issue charging from all sources simultaneously as long as I’m not exceeding my max charge current. But all my charging sources were smart devices too (all Victron components).
