When copying strips between 2 scenes, it wasn't possible to copy animation curves along with strips. In this patch curves are copied into clipboard `ListBase`. When pasted, original curves are moved into temporary `ListBase` and curves in clipboard are moved into scene action. This is because when strips from clipboard have to be renamed, function `SEQ_ensure_unique_name()` does fix RNA paths of curves, but this is done globally for all curves within action. After strips are renamed, restore original curves from backup. Note: This patch handles only fcurves. Drivers and actions are currently not handled anywhere in VSE. Fixes T77530 Reviewed By: sergey Differential Revision: https://developer.blender.org/D13845