yes bro definitely it decreases price
i once had car whose book was snatched (actually snatchers snatched purse from my mama and it went with purse), the car was not snatched ever i got duplicate one in Rs. 2,500 after FIR but every one had a doubt why duplicate book is issued
where is original running certificate etc.. show them copy of fir etc.
so u have to retain copy of fir but even then u will not get original price,new buyer will always pay u less cost due to it unfortunately