Rooney, 26, who has previously attempted to get on Big Brother and launch a pop career, switched the name Andrew to Jedward earlier this month.
"There's a guy who has changed his name to Stephen Jedward Rooney. He used to be called Stephen Andrew Rooney," the Irish twins told DS.
"He gave us a copy of the legal papers, which proves he changed his name a couple of weeks ago. There's also another loads of other fans, who are in a big posse, who say that they going to change their name to Jedward."
John & Edward's debut single 'Under Pressure (Ice Ice Baby)' is available to download from Sunday.