Suggested by Daxxas:

Being able to create copies of other (admin) shopkeepers via command. The copied data should include the trades, the shop type, the data specific to the shop object, .. etc.
For citizens npc shopkeepers it might also be useful if it is somehow possible to create a copy of the npc as well.

Possible command: /shopkeeper copy <shop-id> [<world> <x> <y> <z>]
Creates a shopkeeper based on the shop specified by , at the specified location, or at the player's current/looked-at location. The optional coordinates allow automatic shop creation via console commands, possibly triggered by other plugins.

Additional idea: Allow players to purchase spawn-eggs which will spawn a shopkeeper-copy. Ex. players can purchase a spawn-egg which will create a copy of an existing admin shopkeeper at the location they want.

Example usecase: Players own islands which they can upgrade. The upgrades include pre-created admin shopkeepers being created on the island. When upgraded, the commands would be automatically run to create shopkeeper-copies based on pre-created template shops.

Note: Very specific usecase (therefore low-priority), but at least API-wise it should be made possible to copy the data of one shopkeeper to another shopkeeper.

Similar but different ticket: #1
The linked ticket asks for linking shops to sync their trades, while this ticket doesn't require shops to keep synced, but instead requires all shopkeeper data to be copied.