Two ways to define futamata (ふたまた)

I came upon this sign the other week.

I was　slightly stunned at first.  Several years ago, one of my female friends taught me the word futamata as she related the story of when and why she broke up with her boyfriend.  She'd caught him with another girl, and instead of apologizing or begging forgiveness or promising repentance, he asked her to. . .she wasn't sure how to phrase it as she jumped back and forth between Japanese and English. . .he asked her to let him futamata, or be in a relationship with two girls at the same time.  She refused and resolved that he was scummy.

So when I saw this sign for the Ikebukuro Futamata Koban (koban, of course, being "police box") I wondered what the hell kind of koban it was.  When I got home I googled futamata and found the first of the two definitions that I now know:

Literally: “Double groin“. If you knew the parts of the word,you might be able to guess that it means “having relations with more than one lover.” Typically one of the relationships is illicit.
 
By extension, this word can also be used to describe someone who tries to satisfy two opposing sides of an issue.--from the website Nihon Shock, which I just discovered and quite like, from what I've seen. (url for its entry on futamata: http://nihonshock.com/2010/04/%E4%BA%8C%E8%82%A1/)

That excellent explanation is accompanied by the kanji, 二股、which is different from the 二又 on the sign.

When I looked up ふたまたin an online dictionary, it came up with one definition:  two ways.  That seems fit for a street sign, and for a police box.