Here is the full evidence from 《韻經·十一梗》



▲韻經. 明嘉靖十八年（1539）長水書院刻本.

http://read.nlc.cn/allSearch/searchDetail?searchType=all&showType=1&indexName=data_892&fid=GBZX0301015813

韻經 is a rime dictionary, which means ⿰魚两 must rhyme with 邴寎蛃. If the phonetic component of ⿰魚两 is 两, it clearly does not rhyme with 蛃. I doubt ⿰魚两 is an error form of 𩶁.

The above comment by HUANG Junliang is confusing. In English if you say "I doubt X is Y", it normally means "I don't think that X is Y". Is that what is meant here? It seems rather that the intent is the opposite, in which case "I suspect that ⿰魚两 is an error form of 𩶁." would be better. If that is the case, then I agree with the comment.

丙 and 两 have a close relationship between each other. The paper below discusses etymology and diachronic changes of 丙 and 两. Therefore, ⿰魚两 appearing in Evidence 1 韻經五卷, after 蛃, is reasonable. I don't think we can immediately say ⿰魚两 is an error here.

““丙”与“两”二字形音义关系密切，使用时代互补，皆可证金文“两”为“丙”的分化字，
其量词用法继承自量词“丙””（p.36）
李建平、龙仕平2018 量词“丙”“两”的语源及其历时演变《古汉语研究》2018年03期,pp.32-38.
https://www.cnki.com.cn/article/cjfdtotal-ghyy201803004.htm

《韻經》五卷，成書于嘉靖十七年(1538)，張之象編輯。全書正文包含了古韻和今韻兩部分内容，其古韻參照吳械的《韻補》和楊慎的《轉注古音略》，繼承中又有自己的創見，今韻依據詩韻，并結合實際語音，分韻為一百一十六部。
https://cdmd.cnki.com.cn/Article/CDMD-10394-1015720357.htm

Thanks for demonstration from LI Yuan.
Although ⿰魚两 is obviously the variant of 𩶁, there is no rule for unification of 丙 and 两. As a head character of a dictionary, it has an independent status other from the ones occasionally appear in the text.

Here is another printed version of 韻經:



▲ 韻經（明萬曆刊本）卷3 folio 7a

Suggest to move this character in M-set.