It is illegal to give your friends free copys of games but if it is in the same household I do not think it is illegal but if it isn't this is how you do it!
#1 Copy all of the minecraft files and post it on Mediafire (Remember you have to delete this right after or you will get arrested)
#2 Go to the mediafire link on the other pc
#3 Download and Open
#4 Enjoy Minecraft!
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Non illegal way
#1 Download Minecraft Launcher on the other pc
#2 Log into the same account as the other pc
#3 Enjoy Minecraft!
Thank you for asking!
-NightmareGameee