What is "arial;helvetica" font?

the question is why a text is identified as "arial;helvetica" in OpenOffice

so here is the story: I received an email which I replied to, and then I see in sent that it is garbled (the text that was quoted in the reply)

so what I did is copy and paste some text from the email I received in OpenOffice and it shows that it is "arial;helvetica".

Any help? (Should you move it in a more techy forum, I don't know)