My comment still stands.
Instead of paying $20 for a single key. Pay $100 for the entire replacement keyboard. Remove the E key from the keyboard, then return the keyboard stating the letter E was missing when you received it. When they get it back, they'll refund your $100 and your issue is solved.
KISS: Plug workstation 1 into monitor 1 and workstation 2 into monitor 2. Then use something like Synergy to share the keyboard and mouse between the computers.