Replay will copy items from one store to another. To determine the item, it first looks at the handle to see if the handle already exists within the destination store.
If it does, then Replay will update that item with the same handle. However, it will still create a brand new ID for that item.
Per Shopify's rules, no two items (even if one is a clone of the other) can share the same ID, even if their handle is the same.
If the item does not already exist within your destination store, Replay will copy it as a new item and create a new respective handle and ID.