It would sure help if you provided more explanation.
I assume you are importing photos into the new catalog, and these photos have previously been imported into other catalogs. Is that correct? Or am I way off?
If so, when you Import via COPY or MOVE, and the file already exists on the hard disk in the destination folder, then -2 is automatically added (and -3 and so on).
Why are you creating another catalog with the same photos as other catalogs? Please explain. This is usually considered to be a very poor practice that leads to confusion and extra work, rather than leading to actual benefits. But anyway, my answer to the question of how to stop this is for you to use one catalog.
The OS does this. Sounds like you COPY the photos during import, and you copy them to the same folder. If you import images that are already on your drive, then use ADD in the top middle of the import dialog. As @dj_paige already mentioned, why create a new catalog with the same photos in the first place?
The simplest way around the problem would be to use your operating system to, after the catalog is created, rename it to whatever you wanted to be named and then double-click on it. Lightroom will open it and will remember it with its new name.