Can hair transplant damage the existing hair at the recipient area? + Propecia (Photo)

I had FUE hair transplant done in Istanbul last week (4000 grafs). I had low density thick hair in the middle front area (please see pictures). The implanted hair covered the entire area (please see pictures). Could the HT damage my existing thick hair at the recipient area? Or it should grow back normally. Also, does Propecia helps if I use it now? Please advise. Thank you.