--- Quote Start ---
Some FPGA tools use random numbers to make routing decisions. If this is the case with your MAX+ tool, you won't be able to reproduce the build without the random number seed used to create the build.
--- Quote End ---
This is true of all fit engines, they are fed a seed value to get different fit results. But this seed is based on source-code and manual seed value. Given the same tool version on the same platform with the same source code and same fit seed, you should get identical results (and this is a very important thing).