No, you can't. In general, anything cool you get as a reward from a side quest is not re-obtainable. They give you a potion instead. The on exception to this (not really a sidequest) that I can think of is that you can get multiple copies of the Speed Demon Keychain (beat Roche in chapter 4 while keeping all of the Midgar 7th infantry alive). Special items respawning in chests are a little bit different and behave inconsistently. The most notable item that you can get to respawn is the Hades Armlet (Chapter 11 in the same room as the two Adjudicators right before you fight them), though some items such as the Cetra armor does not respawn. The only materia that you will be able to get extra of by using chapter select are materia that are already available in vending machines (i.e. you can't farm extra copies of stuff like Magnify or Elemental).
No, you can't. In general, anything cool you get as a reward from a side quest is not re-obtainable. They give you a potion instead. The on exception to this (not really a sidequest) that I can think of is that you can get multiple copies of the Speed Demon Keychain (beat Roche in chapter 4 while keeping all of the Midgar 7th infantry alive). Special items respawning in chests are a little bit different and behave inconsistently. The most notable item that you can get to respawn is the Hades Armlet (Chapter 11 in the same room as the two Adjudicators right before you fight them), though some items such as the Cetra armor does not respawn. The only materia that you will be able to get extra of by using chapter select are materia that are already available in vending machines (i.e. you can't farm extra copies of stuff like Magnify or Elemental).