Charger by definition is active circuit that controls current. So while it's possible to do just that, it means designing and building two such circuits; i.e., two "chargers". Guesstimating from your question, you are likely after a simple solution, which does not exist; easiest is to either charge in parallel in a dumb way (see below), or buy two completely separate chargers.
Note that you can just parallel the packs and work with the single charger, but only after you have charged or discharged the packs separately to the same state-of-charge so that their voltages match closely. Be very careful here; a large voltage mismatch causes massive currents during the time of making the parallel connection, exceeding the current ratings (especially the max charge current rating of the pack which happened to be at lower voltage). Paralleling packs is hence impractical when you need to separate them again for discharge. Semi-permanent paralleling is manageable.
Even with permanent parallel connection of series packs, each should have their own cell-level BMS; paralleling every balance tap as well (measuring the voltages match beforehand, again!) gets rid of this requirement.