That kind of depends on what the data looks like, but I think a simple copy-paste approach is your best bet. combining the two output files into one.
The things you should consider before doing this are:
1. Is the data really from the same sample? Did you take the exact same material and measure twice, because sample-to-sample differences can occur (depending on what you measure)
2. Is the data, roughly, in the same scale? If not it may be wise to normalize before combining
I have to ask - why would you want to combine both into one spectrum? Wouldn't it make more sense just to provide both?