Only 20th Century Fox, which controls the X-Men rights, will be able to use the characters' superhero titles, while Marvel can use the names Wanda and Pietro, according to The Hollywood Reporter's Borys Kit.
"Following up a bit on @DrewAtHitFix's take on Quicksilver: Heard that Fox can actually use the Quicksilver and Scarlet Witch names," he wrote on Twitter.
"Marvel can use the the names Pietro and Wanda."
Marvel Studios - which controls the Avengers properties - and Fox - which holds the X-Men movie rights - both have a claim on the characters.
Scarlet Witch and Quicksilver, the children of Magneto, first debuted in X-Men but have been important members of the Avengers over the years.
It is believed that the use of the names has been divided to prevent the franchises from being confused by audiences.
Joss Whedon has teased the appearance of the pair in Avengers 2. However, X-Men: Days of Future Past director Bryan Singer revealed this week that American Horror Story's Evan Peters will portray Pietro Maximoff in his upcoming movie, which is currently shooting.
It has also been claimed that Avengers 2 will not be able to refer to the twins as mutants.
The Avengers - comic to screen in pictures: