Summary

After copying entire lines (i.e. without selection) with multiple cursors, pasting with a different number of cursors adds extra newlines between the pasted lines.

Description

As noted by @notpeter in #34797 (comment) (emphasis mine):

Multicursor cut/copy in vscode does not use this alternate line-wise paste mode and pastes to the cursor position(s) like a normal clipboard action. Multicursor in Jetbrains and Sublime have an odd behavior -- when cut/copying two adjacent lines if you paste to a single cursor you will get an extra line break between the pasted lines. (this makes cut/paste non-symmetrical). If pasting two lines to two cursors, Sublime will give you four lines separated by two linebreaks each; jetbrains will give you two lines seperated by two newlines each. I find all of these behaviors unintuitive.

Steps to reproduce:

1. Place multiple (N > 1) cursors on separate lines
2. Copy (without selecting any text, which copies entire lines)
3. Paste using a different number of cursors (including just 1 cursor)

Expected Behavior: N lines are pasted at each cursor
Actual Behavior: 2N-1 lines are pasted at each cursor (the original N lines are interleaved with extra newlines)

Zed Version and System Specs

Zed: v0.209.4 (Zed)
OS: macOS 15.7.1
Memory: 16 GiB
Architecture: x86_64