Merging before transformation

Hi everyone,

Is it possible to merge 2 Excel files in Power BI before any transformation ? 

In fact, i have so much lines that Excel crashes when I try to paste the lines into one only file.

So, I'm trying to do it in Power BI and the transformations are the same for both files. If yes, how can I do it? 

Someone could help me?

Thanks in advance for your help.