Are you the buyer or the seller?
If you’re the seller, you shouldn’t even be bidding on your own item, but I think you know that.
If you’re the buyer and using the same ID, all you’ll be doing is increasing your maximum bid. You won’t be bidding against yourself.
If you try bidding against yourself using a different ID, that could set off red flags for the patrol bots. I wouldn’t recommend that. Your bids may be interpreted as colluding with the seller, or shill bids.