better put like this:
If you want that a specific pptp user(let's say user: hack-back) always get the same remoteip (10.10.10.1 in your case, because you want to run the some kind of server software at your pptp remoteip), you can achieve this by editing the
# client server secret IP addresses
Bob * pass123 *
hack-back * pass123 10.10.10.1
So, in this case study, user "Bob" will get random ip from specified remoteip range, while user "hack-back" will always get the same remoteip - 10.10.10.1
Also, while editing the file above please note that you must press the TAB key between client,server,secret,IP addresses fields.