Dual Caliber Rifle

Has anyone heard of a dual caliber rifle capable of firing both 5.56mm and 7.62mm rounds?
I think it had two barrels for each caliber but I can't find any more details of such a weapon!
Any other info of this or something similar then please post me a reply.
Much Thanks,
DirtDawg

I couldn't find any dual firing rifle that fires a 5.56 and 7.62 rounds the only dual firing rifles I know are the ones being developed that can fire an air burst grenade round and regular NATO round.

Whats the point of a dual caliber weapon. It only gets in the way of how much ammo you can carry. Plus the gun gets over complex.

I have heard of conversions for AK47, never actually seen one work but Im sure if they can make conversions then its possible to make a dual firing rifle. However Id be concerned about its accuracy and range.