vBulletin Overwriting - Two titles same name

[klinzter]

Hello Everyone,
I have vbulletin 3.5.2 in my website and Im having some trouble with a section
called (How-To) in there my friends and I post information with titles like
TXT-942, TXT-462, TXT-203 etc....

we have around 90 how-tos and sometimes we have to delete some because they are
already in the database lets say I do #110 today and in one week a friend
does #110 too and he posts it in the forum.. is there anyway to create
something that doesnt let the user write repeated how to's ?
so it doesnt have two title with the same name?

Lets say in title you type TXT-012 then a button called seach
right next to it, if nothing is found then you are ready to
post if something is found just to show the link or something..
thanks