1997 Jeep Laredo May Purchasing Grand Cherokee Gentleman There 100 000 Miles On

i may be purchasing a 1997 jeep grand cherokee laredo and the gentleman said there were 100,000 miles on it i test drove it yesterday the mileage said 199,999 miles he said he just got engine replaced and the mileage from that vehicle transferred to the jeep is that possible he said he had the papers i did not see them because idont know if i am going to get this vehicle or not does the mileage transfer over i am confused