Do you mean buyer has placed 3 same bids? Are you the seller? Only a seller can remove bids.
There's nothing suspicious about one bidder placing the same bid a few times, they are just upping their bid each time, and as they cannot bid against themselves, the highest bid will only show when matched or a bid is placed higher.
It's not shill bidding it's either someone who perhaps doesn't know how to bid , and does not understand why their high bid is not showing so places another and another. Or, a clever bidder who is showing that their latest hidden bid is perhaps substantially higher than the one showing , so the last bidder knows they'll have to place a much higher bid to be able to compete.
@felterr-20
