more details will be useful.
Medicals are asked again after 10-11 month(1 or 2 months before they expire) if a decision hasn't been made. This only applies to people outside Canada mostly. People inside Canada have their medicals extended.
However, PCC is asked again under the same situation but for both inside and outside applicants but mostly inside applicants.
Also, keep in mind that if they are asking again too soon, that might mean that they never received it. People have had their application rejected because CIC says they didn't send the documents they requested when they did send them.
The best you can do is comply with their request asap. good luck.