Sometime we created tables just for testing purpose within AOT and later on we delete these tables. In such cases we don't care about the IDs which are created for each table. There is a way to use these system generated IDs for other newly created tables.
You can do this by following steps;
1. Export the table with its current id.
2. Delete the table
3. Edit the xpo file and change the id to what you want
4. Import the xpo file with the id option checked. As long as the id is not used by something else, then it should get imported with that id.