It's a very bad idea to have the exact same tags on a bunch of listings, as those listings will then be competing against each other in Search. You really should try to vary your tags as much as possible (while still keeping them relevant to your items) to maximise the number of search terms that will surface your listings when buyers search for items like yours.
For example, you might tag an item as "doll's pink dress" because that's what you made, but that dress won't be found if a buyer searches for "doll's party dress". You need to think of all the ways that someone might describe your item when you write the tags for that listing.
