Tellers deal 400 damage so they oneshot a T-70.
Tellers is the normal mine. You are thinking on Riegel mines which if IIRC do less damage than Tellers.
I had to test this to believe it, but you're both right. The Teller does 1-shot a T70, and the Riegel, which I was thinking of in my previous post, does slightly less damage (360-380?). I seem to have had the two confused for years. My assumption had always been that the doc-locked, LV-deployed, heavy anti-tank mine was more powerful.
The followup questions would then be:
Why does the tooltip call it the "Riegel-43 heavy anti-tank mine" if it does less damage, and why does it cost the same as the normal Teller?
This seems like a tool-tip issue. I can't find any description of the historical Riegel-43 being referred to as a "heavy" anti-tank mine, and it in fact weighs approximately the same as both the Tellermine 42, and only slightly more than the '43. The Riegel was also only about 75% as powerful as the Tellers.