@Invader_Retro you're not at fault, the one at fault is steffortless who numbered the chapters incorrectly.
Steffortless was using the magazine raws (you can confirm this for yourself as all of steffortless' chapters have gangan joker marketing on the pages), yet he was numbering the chapters as being part of the volume releases, which was incorrect. This is the problem, the chapters came out in a different order in the magazine, and then re-ordered in the volumes. But because stefortless added vol 1 and 2 to the chapter names, it's now conflicting with the volume release.
Stefortless should have simply used the chapter field and not added the volume field when doing his releases.
There are two ways to fix this:
One would be to do what
Kemono Michi does and have the volume numbering be the primary numbering system and then in parenthesis you'd put the magazine chapter number. This would clarify what came out when. This requires more effort though, as you have to compare two releases.
The other solution would simply be to renumber all of stefortless' releases to match up with the volume numbering. This would lose the information of the magazine numbering, but it's faster and stefortless' releases would finally be properly inserted in the page and you'd finally avoid complaints about repeated chapters.