Most veteran eBay members know that people use multiple IDs on eBay. Sure enough, survey respondents cited a variety of reasons for holding multiple eBay user IDs. Here are some of the more interesting answers:

Vigilantism Is Alive on eBay!
Many people get upset when sellers misrepresent items for sale, feeling that even if the seller doesn't know the authenticity of an item, they should research it before putting it up for sale. Well, one survey respondent said they use a separate eBay ID to bid on items that are reproduction antiques when the seller does not reveal that fact; they win the auction and then don't pay the seller.

Santa Clause Is Coming
Several people said they use a separate ID for gift-buying. "The 2nd ID I use to buy family members gifts... they look on my normal ID too much, so I have to keep their gifts a secret!" "I needed a second account to be able to buy items for Christmas, etc."

Dog-Eat-Dog World
"It is very common for die-hard collectors to monitor the bidding activities of competitors, so this is my way of protecting myself." We know of some users who troll through eBay looking for items that the seller has mis-categorized or misspelled. They can then buy the item at a bargain (since no one else can find it!). Sharp collectors keep an eye on these alert individuals in the hopes of snatching the bargains for themselves.

Retaliation Avoidance
"I use another ID for buying and don't hesitate to leave feedback when the item is not as described." Although retaliatory feedback is banned on eBay, many buyers and sellers fear that if they leave a negative feedback for someone, their trading partner may very well leave a negative feedback for them in return.

The "Mom" Factor
"So I can buy and sell without 100 of my friends and relatives knowing what I'm doing." "So mom does not know what I buy."

Shill Bidding
Yes, one respondent owned up to shill bidding. This is when you bid on your own item (or that of an accomplice) to raise the selling price.

Boarding & Bitching
"I have one ID for buying and selling and one for boarding and bitching." Judging by some of the behavior on message boards and chat forums, it doesn't surprise us that people want a second identity for posting versus buying/selling!

"Mood Ring" Phenomenon
"I create names according to what mood I am in. I have over 200 eBay names and over 900 email addresses."

Some other answers:
"One ID is only protecting a personal 'trademark.'"
"Selling items for a friend under another ID."
"Personal reasons."

Here's our favorite: "Because it's allowed."