on different sheets and even strips i've seen different results. i think a stronger spot on blotter paper is called a "hot spot". sometimes more lsd gets absorbed on one part of a sheet, and there can just be tiny areas that are "hot spots" even on properly laid blotter, but generally blotter is pretty evenly laid even though i've had some dealers where i've gotten a ten strip of white tabs where part of the strip is noticably soaked with more liquid or whatever, and that part of the paper was way way stronger. i don't think you can really tell if that's happening as well on blotter paper with colored designs.
there will be less lsd on the tab if you cut it in half though most likely, so it will be a lighter trip... you can also put the tab in alcohol or spring water and mix that to get more exact results if you are worried about an inconsistently laid tab. i think people use alcohol cause it's more sterile if you let it sit for long. you only use a little bit, so when you take it it's just a sip of alcohol, not to get drunk or anything.