Messenger app shows an mms as being from a group

[Rick Spencer]

Steps:

1. Receive a message with an attached picture
2. Note that the message is sent to a group
3. Click on the little contacts icon in the top right

Result:
It shows two contacts, the sender and also your phone number

Expected:
It only shows the sender

[Rick Spencer (rick-rickspencer3)]

Note that I have t-mobile

To whoever made mms start working with t-mobile in the US: thanks! ;)