I helped him on IRC, then realized I should probably post here in case someone else has the same question.
[13.48.17] <&ddunk> "Because Messenger Plus! analyses messages received only when they reach the chat window, it is not possible to determine exactly from which contact the message came from."
[13.48.26] <&ddunk> so yes, it's normal for that to happen
[13.48.49] <Dhaya> oh thank you
[13.49.30] <Dhaya> oh that's the text in the Remark section
... I think i have forgotten to read carefully that part