As far as I can tell, d2d
and 2dd
have exactly the same effect.
I'm curious – ignoring any remappings of d
and 2
, are there any cases in which d2d
and 2dd
will produce a different result?
As far as I can tell, I'm curious – ignoring any remappings of 


No. According to the Vim manual
Both commands will always produce the same result. If there is more than one count, then each count will be multiplied together. For example 2d2d is equivalent to 4dd, and 3d3d is equivalent to 9dd. If you're only interested in just deleting two lines, you can save yourself an extra keystroke by using dj. 

