But I would also approach the problem slightly differently.
Configure the first router with the settings necessary and use the command COPY RUN STAR to save it to NVRAM. Copy and paste the text file into a text editor and then copy and paste that file into the running-config of the second router. Once in the running-config, make the necessary changes to differentiate it from the first router and use COPY RUN STAR to save it into NVRAM on the second router and the job is done.
Its worth keeping the text file on a network share then just in case.
Depending on the size of the configuration, it might be 15-30 minutes worth of work but it is the best solution I could think of.