This one is strange but its been doing it reliably for sometime.

If I move to the beginning of a line, type 'iabc<esc>'
then hit enter (go to next line) and type '.' what gets entered is the first character of the previous line then the 'bc'.

Example:
Start with:
This is one line
Another line
more lines

Point to the 'T' type 'iabc<esc><cr>.'
and you get:
abcThis is one line
TbcAnother line
more lines

oddly enough if I then type '<esc>iabc<esc><cr>.' it works and will continue to work for the remainder of the lines.