Sources: [한국어의 불규칙 활용](https://ko.wikipedia.org/wiki/%ED%95%9C%EA%B5%AD%EC%96%B4%EC%9D%98_%EB%B6%88%EA%B7%9C%EC%B9%99_%ED%99%9C%EC%9A%A9#.E3.85.82_.EB.B6.88.EA.B7.9C.EC.B9.99_.ED.99.9C.EC.9A.A9)  
[[Grammar] ‘ㅂ’ 불규칙 : ‘ㅂ’ irregular verb/adjective](https://funkorean4u.wordpress.com/2014/07/19/grammar-%E3%85%82-%EB%B6%88%EA%B7%9C%EC%B9%99-%E3%85%82-irregular-verbadjective/)

I tried searching the internet, but 돕다 and 곱다 likely seem to be the only irregularities (of ㅂ irregulars,) and I personally too can't think of any other similar examples. You could view the two as exceptional ones.

Some explanations on the internet claim that this kind of exception occur when the verb stem is single syllable. But I find them not accurate, since we have 깁다, which is conjugated as 기워.