There are multiple versions of the exact same Engraving chests. Some examples:
Uncommon Class Selection:
- Uncommon Class Engraving Recipe Selection Chest
- Uncommon Engraving Recipe Chest
- Uncommon Engraving Recipe Selection Chest (Class Exclusive)
Uncommon Selection:
- Uncommon Combat Engraving Recipe Selection Chest
- Uncommon Combat Engraving Recipe Selection Pouch
- Uncommon Battle Engraving Recipe Selection Pouch
Uncommon Random:
- Uncommon Battle Engraving Recipe Pouch
Rare Class Selection:
- Rare Class Engraving Recipe Selection Chest
- Rare Class Engraving Recipe Selection Chest
- Rare Engraving Recipe Selection Chest (Class Exclusive)
- Rare Engraving Recipe Selection Chest (Class Exclusive)
Rare Selection:
- Rare Combat Engraving Recipe Selection Chest
- Rare Combat Engraving Recipe Selection Chest
- Rare Combat Engraving Recipe Selection Pouch
- Rare Battle Engraving Recipe Selection Pouch
Rare Random:
-
Rare Battle Engraving Recipe Pouch
-
Uncommon / Rare Random
-
Harmony Battle Engraving Recipe Pouch
Epic Class Selection:
- Epic Class Engraving Recipe Selection Chest
- Epic Class Engraving Recipe Selection Chest
- Epic Engraving Recipe Selection Chest (Class Exclusive)
Epic Selection:
- Epic Combat Engraving Recipe Selection Chest
- Epic Combat Engraving Recipe Selection Chest

This isn’t even a complete list. The engraving chests purchased from the Anguished Isle vendor are yet another unique item and do not stack with any of the above.
This makes these items very hard to understand, or keep track of just how many selection chests you actually have (because they could be split across 3 or 4 different stacks).