you can absolutely upload in black and white as long as you can read it... a document color has nothing to do with authenticity!
Different scanners have different settings... so go for which is most readable for u!
I faced almost same challenge as u, i was using the HP Photosmart printer/scanner, when i tried scanning in color, trust me it was horrible, it picked photos from the document which might include the company logo and other stuff. I was left with no option than to scan as a pdf doc(black & white).