Google Groups: can't subscribe multiple addresses

I've been subscribed to a group for a few years and last night via my personal 
domain, and just tried to add a second subscription for my Google account by 
sending mail from gmail.com to $group+subscribe@googlegroups.com.  

This resulted in a very surprising message to my home domain that I am already 
subscribed.  I double-checked the outbound message at gmail and there is no 
indication at all in the headers of my home domain so I was a bit mystified as 
to how that happened.

Next I went to https://groups.google.com/forum/#!forum/$group while logged into 
Google to see if I could just click a "Follow this group" button or something.  
Instead it shows I am already a member, with email going to my home domain as 
expected.  This is apparently where the correlation between my addresses comes 
from, and what makes my desired scenario impossible.

While there are some obvious workarounds, such as remailing a copy from my home 
domain back to Google, or enabling a filter at Google to forward a copy to 
home, it is unhelpful and unintuitive to have to set things up this way.  There 
is a multi-decades long tradition on the Internet of a single user being able 
to join a list from multiple addresses; please allow it for Google Groups.

Original issue reported on code.google.com by vtt...@gmail.com on 21 Aug 2014 at 2:20

google-code-export / googlebugs

Google Groups: can't subscribe multiple addresses #619