Yes, the flashtool will prevent it It will compare 2 checksums.
1. From the cdrw drive itself (in your case cdd 4851) with
2. the firmware file (cdd4851)
If you open the firmware fiel with a HEX-Editor you will find the string "philips cdd4851 flash file" 2 times.
At the begin and in the middle.
Now if you are smart you can take the firmware from the cdrw1610a (cdd4911) and rename the 2 strings to cdd4851 .
BUT the cdrw1610a uses another chipset teh the pcrw1208k.
So you will end with a dead drive.
Ans alternative you could try mtkflash http://wald.heim.at/sherwood/530742/dvd/mt/index.html
Use it on your own risk. Make sure that bad flashing can destroy your drive completly.