Yes, you are seeing double.
“Literally every department was involved.
It was like a group swap.

Rachel Weisz as Elliot and Beverly Mantle in ‘Dead Ringers’.Prime Video
We all swapped together and then the other actors had to adjust as well.”
In essence, every scene had to be shot twice.
While Weisz was playing one Mantle, her double Kitty Hawthorne would stand in for the other.

Rachel Weisz and Rachel Weisz in ‘Dead Ringers’.Amazon Prime
“It was really extraordinary,” Ehle tells EW.
Then they would go away to swap clothes and hair and everything.
We would be given earpieces that would play the last take and mime it out.
Nobody spoke apart from Rachel as the new twin."
It was a precarious process.
Meade recalls that one camera monitor couldn’t be touched during the second run-through.
If it was nudged, the whole shot would have to be done again.
As difficult as it sounds, Weisz says everyone eventually adapted to the delicate operation.
“We got it down to like 20 minutes.
I’d just get into hair and makeup and change clothes even underwear, strangely!”
Turning to showrunner Alice Birch, Weisz adds, “Sorry!
I never told you that.”
All six episodes ofDead Ringerswill be available on Prime Video on April 21.