Hopefully it's not cancerous based upon saying, "possibly a recurrence." A difference in biopsies can matter, sometimes, and maybe not, but is an important aspect for it being done correctly, and it's pathology also. The doctors know best, and usually want to remove minimum of tissue, but enough surrounding for clear margins, the entire lesion or part of for testing. In the office setting, it sounds like it could have been exisional, an incisional, punch biopsy or a FNAB, not being familiar with the particulars with the case. An incisional is preferred over an excisional, to remove a sample, rather than the whole tissue not knowing clear margins at the time, and then having to go back later if it wasn't all clear or recurred. Even if everything was done right, it could be synchronous, monochronous or a secondary cancer from the "field cancerization" and that's where sometimes radiation or Chemoradiation is used to get more of a larger area.
Here is an OCF link describing the different type of biopsies to help better understand than I can explain.
http://www.oralcancerfoundation.org/discovery-diagnosis/detailed-biopsy.phpGood luck with everything.
