The only way that might be possible is if the person who is beating you is on the same network as you. Maybe in the same cable modem block or something like that. It's highly unlikely.
The most likely reason is usually the correct one. In this case it's just that they're bidding more than you. Perhaps they are doing research on those types of items and see that there are people that snipe them so they prepare for this by bidding higher as an example.
I suppose you could enter your next few snipes here: https://www.auctionsniper.com to try and see but it'd likely be just a coincidence if you ended up winning those. But perhaps you'll lose them as well and the question will have been answered.