Emulator

Game Name?
Any.

Game ID?
Any.

What's the problem? Describe what went wrong in few words.
When using Dolphin with an Nvidia GPU, using D3D11, and Real XFB enabled, every fifth column is replaced with a duplicate of the one to the right.

What did you expect to happen instead?
No pixel defects with Real XFB enabled.

What steps will reproduce the problem?

1. Install Dolphin.
2. In graphics properties, set D3D11, 1X IR, enable Real XFB, optionally check "Auto-adjust window size"
3. Launch any game. (Brawl menu displays glitch well)

Dolphin 3.5 and 3.5-367 are old versions of Dolphin that have
known issues and bugs, so don't report issues about them and test the
latest Dolphin version first.
Which versions of Dolphin did you test on?
4.0-2263, 4.0 stable (D3D9 and D3D11), 3.0 (D3D9 and D3D11)

Does using an older version of Dolphin solve your issue? If yes, which
versions of Dolphin used to work?
As far as I know, no.

What are your PC specifications? (including, but not limited to: Operating
System, CPU and GPU)
Windows 7 x64, Intel i5 3570K @4.0 GHz, Asus Nvidia GTX 660

Is there any other relevant information? (e.g. logs, screenshots,
configuration files)
https://imgur.com/pQtlnkl
The jaggies become less noticeable when you increase the IR, because the sampling position is only off by about 1 pixel in the source image, rather than one destination XFB pixel. With higher IRs, the incorrect position is very close to the correct position as a percentage of the entire width. With 1xIR, the incorrect position is an entire pixel away.

I don't know why this bug actually happens.