Yes and yes, so take your pick.
If you aren’t seeing two Venn diagrams, you’re okay.
As I suspected, the gist of the joke is contained within the definition of the subject matter. I had to look it up but I’ll save you the trouble: (Wikipedia) Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, diagonally (i.e., both vertically and horizontally), or rotationally in relation to each other.
Often accompanied by one too many drinks before the drive home.
I have a diploma in diplopia.