I thing there in no way for a checker to find out if a cache is adopted. I don't thing there is any way to readability find out from the cache page if the adoption note is removed.
Petroleum Tango is a series in Sweden with caches near petrol stations. Anyone can place them. You should use the same text and contact someone for a unique number.
Here are another example i found after a quick look at caches with # in Sweden
http://coord.info/GC3C1R8
http://coord.info/GC3C1QA
If you assume same CO=series
The problem with series and assume the same CO is that you get false positive pairs.
The problem with one CO and identical name not in a series is a false negative pair.
The real problem is that it is not appropriate to make a knowing misleading checker.
If you cant create it correct you generally should not tag it. Especially if you can get false positives and incorrect logs. False negative is better in my opinion if you add some text in the tag description and preferably in the checker.