Why do I have to pay a self-installation plus fee in addition to a professional installation fee?

I'm moving to a new home and want to transfer service. Comcast is charging me $39.99 for a professional installation. 

I also want to upgrade service from my 800Mbps plan onto the 1000Mbps which is advertised as -$39 a month for a year. In the fine print it mentions I have to pay a $39.99 Self Installation Plus Fee as well.

Why do I need to pay two separate $39.99 installation fees for changing service to a new location? How can I only get charged for one installation?

If it's two separate charges, I may as well just cancel my Xfinity service altogether and start a new account and do one installation to only get a one time $39.99 fee - that seems very counterproductive. The chat support is actually insulting to not be able to get an answer to a question. Hopefully I can get help using a forum....