Well, you originally chose the name Kelvin to begin with which is indeed a commonly used forename. Choosing a generally used name was mistake on your behalf. Besides like you said "nickname is a combination, an imagination." Perhaps you could have avoided this by following this.
Nothing on the server states that you have ownership to this name especially with it being so common. I can agree if your name were more unique like "DarkForce64" and another player would have the nickname "DarkForce65" but for a name used worldwide, you have no intellectual property rights or something over this name.
Besides, you also said "This is a game,not a real life." which is exactly true therefore it shouldn't be a massive deal.
While it does suck that there is people using a similar name as you which can cause to a confusion I personally won't be taking action against this, regardless of how many years you have played as at the moment this shitty attitude isn't really persuading me in the slightest.
tl;dr - forenames are not exclusive and if you use a forename as a username you do not own exclusive membership of that name.
Same applies for character names e.g TommyVercetti848 then whining that theres another Tommy or Vercetti playing is just absurd. If anyone in that case has rights its Rockstar Games.
Just a haha for this answer. It sounds too funny when an ingame inactive player like you try to take decisions. You better let other staff members think about this situation. You are not the right man around no matter what position you are in.
Inactive? I've been active lately ingame (just not the past few days as I have a social life at the weekend), on forums and helping players other staff etc on IRC whenever I'm available.
Kelvin------------
14, 12, 11, 09, 09, 02, - March
24, 23, 20, 19, 18, 17, 14, 13, 10, 02, - February
Myself------------
11, 10, 09, 08, 07, 06, 04, 03, 02, 01, - March
29, 28, 27, 26, 20, 19, 18, 17, 13, 12, 11, 10, 09, 07 - February
Besides, even on the missing days I have been handling player reports on the forum, discussing matters with other staff, helping with add new features to the server + testing, reorganizing the forum (e.g the lag/delay guide I made the other day), and currently at the moment working on some stuff for the server and vc-mp community in general. It's hardly inactive lol.
I don't even feel like this is debate worthy either so stopping at this point (atleast for my own sanity) is the best option. Although obviously this is a community and other members are open to discuss and Darfy and Morphine have still yet to comment if there available. Currently as it stands myself and Adtec who have been both around in this community since 2005 disagree with this. We won't be kicking every player with a name similar to another players nickname, I would only kick if it was justified under a given situation where it is clear that the person is attempting to impersonate another player or member of staff.