A Windows computer’s ID is its computer name/domain (or workgroup) name combination. Lansweeper will never allow two computers with the same computer name and domain name to reside in the same database. If you attempt to scan multiple computers with the same computer name/domain name combination, these computers will start overwriting each other in the database.
If you have two Windows computers with the same domain name/computer name combination, you can theoretically get them both into a single database by scanning the first asset, renaming it in Lansweeper (by hitting the Edit Asset button on the asset page) and then scanning the second asset. However, this will cause issues upon rescanning. The Lansweeper service will still connect to the assets’ real name and will still try to look for that name in the database. In other words: the asset page you manually changed will never be updated and the asset page with the “correct” asset name will continuously be overwritten if you keep scanning both assets.