@zhangshuang Unfortunately machine translation failed to translate your message clearly. Are you asking whether it is ok to name your skeleton e.g. skeletonname2 or skeletonname_2 and at the same time have the atlas page name append a suffix 2? If this is your question: Yes, it is ok, any number suffix will just be appended at the end (resulting in e.g. skeletonname22).

If this is not your question, could you please describe with an example what you want to have as a result, what you got as a result, and what you are afraid would be a problem?

@zhangshuang Thanks for the clarification. I'm sorry to say that 4.1 does not receive any updates any longer, and that the atlas page number suffix format can't be configured, it is fixed.

If your application relies on a fixed name, you could use a shell or batch script (.sh or .bat) to rename the files and to also replace the respective name in the .atlas.txt file as well.
You can see our export/runtimes.sh script as an example script here where it renames atlas page texture names and adjusts the names in the .atlas.txt file. The basic call with sed would be like this:

sed -i "s/name_2.png/name2.png/g" "targetdir/name.atlas.txt"

zhangshuang spine-unity 3.8 supports Unity 2017.1-2020.3, so later versions are not supported. The Unity versions supported by the various spine-unity runtime versions are listed on the download page.:
https://zh.esotericsoftware.com/spine-unity-download#%E6%97%A9%E6%9C%9F%E7%89%88%E6%9C%AC