Some beatmaps have a tempo twice the actual tempo.
For example:
https://osu.ppy.sh/b/127015
https://osu.ppy.sh/b/510873
And some have a tempo half of the actual tempo:
https://osu.ppy.sh/b/26945
For example:
https://osu.ppy.sh/b/127015
https://osu.ppy.sh/b/510873
And some have a tempo half of the actual tempo:
https://osu.ppy.sh/b/26945