Can I replace a 48" glass sliding closet door with two 24" doors?
In my area it is common in rental units to install panel doors in lieu of mirrored doors. We buy the mirrored door track, frame, roller, and hardware kits but with no mirrors. They call it a "knock-down" kit. We then cut wood or composite panels to fit where the glass would go. The manufacturer even gave us a table with net mirror glass dimensions, to use when sizing the wood panels. Check with a local high-volume window and door shop. You might even be able to get the kits from a "big-box" hardware store but I prefer to work with the guys at the sash and door shop for the personal service and expertise.

You might even be able to use your old frame and hardware, measure carefully first, then take apart the frames (they are screwed together) and cut wood panels to fit.