Were Two Of The Bee Gees Twins?

Yes...the twins Robin Hugh Gibb and Maurice Ernest Gibb Were born on 22 December 1949.

Indeed they were. The Bee Gees were a singing trio that became one of the most successful bands of all time. The group's name is said to be derived from the initials B.G, standing for Brothers Gibb.
The brothers were lead vocalist Barry Gibb and his younger twin brothers, co-lead vocalist Robin and keyboard and guitarist Maurice. They were all born in Douglas on the Isle of Man in the 1940's, but grew up in Manchester in the UK and later in Redcliffe in Australia.
The brothers were successful for more than forty years and were notable for their instantly recognizable high-voice style. Barry was noted for singing in an R & B falsetto voice on a number of songs and all three brothers co-wrote most of their hits.
Sadly Maurice died from complications of a twisted intestine in January 2003 and although the brothers initially decided to continue with the band name in memory of their brother, they decided to disband. Since their brother's death  both Robin and Barry have recorded independently of each other. In February 2006, they reunited on stage for a Miami charity concert. It was their first public performance since the death of Maurice.