2 chargers connected to one battery bank?

You can connect similar chargers in paralell but it sounds like the new charge is more advanced so it's probibly not a good idea. Your batterys might be in series-paralell , in which case you can charge each pair with each charger. The problem with that is that banks will not reach full charge at same time which is ok if you wait until both pair are at full charge. Otherwise the lesser charged pair will be unduely stressed under load. You should read for yourself what battery and charger manufactures say about quick charging depleted batteries. Throughing a 100 amp charge on a battery for secounds to replinish the power consumed by say starting an engine has a far different effect than throwing 100amps on a heavyly discharged battery. Esp repeatedly doing it.