It is hard to consider such situation but yes, it is possible that there are different "thicknesses" in one field according to the rules.
2.3.1 The black line, 1-2 cm wide, may be made with standard electrical insulating tape or printed onto paper or other materials. The black line forms a path on the floor. (The grid lines indicated in the drawings are for reference only and competitors can expect tiles to be duplicated, added and/ or omitted.)
Line width will depends on the material prepared by the local competition organizer. However, I didn't have a chance to see such funny fields in my experience in this 10 years, but don't forget the width naturally changes in a little when the electrical insulating tape was made bent.
2020 RCJ Rescue TC/OC