Environment

Windows build number: Version 10.0.18363.1198
Windows Terminal version (if applicable):

Steps to reproduce

1. Open a cmd shell in conhost.
2. Output some text from a double byte character set (e.g. こんにちは).
3. Output the same text with the characters repeated (e.g. ここんんににちちはは).
4. Select an instance of the text from step 2.
5. Press Ctrl+Shift+4 to search for matching text and color it in green.

Expected behavior

All the instances of text from step 2 should be colored in green.

Actual behavior

The search mistakenly matches the instances of text from step 3 (where the characters are repeated).

The problem is caused by the code that extracts the search text from the screen buffer here:

It's copying one screen cell at a time from the selected range, but that means each character is copied twice with DBCS text, since there are two cells per character.