Yes. First, the Constitution specifies that if a work is ever successfully nominated, it cannot be nominated again, so MoR can only be done once. (Examining the categories carefully, pg 6-7, it may or may not be technically possible that MoR could be nominated in one year for Best Novel and then Eliezer himself - on the strength of fandom arising from MoR - nominated for 'Best Fan Writer'.)

Second, the rules get very complex on pg 8 about multiple categories, which is why I did not bring it up before:

3.8.2: The Worldcon Committee shall determine the eligibility of nominees and assignment to the proper category of works nominated in more than one category.

3.8.3: Any nominations for "No Award" shall be disregarded.

3.8.4: If a nominee appears on a nomination ballot more than once in any one category, only one nomination shall be counted in that category.

3.8.5: No nominee shall appear on the final Award ballot if it received fewer nominations than five percent (5%) of the number of ballots listing one or more nominations in that category, except that the first three eligible nominees, including any ties, shall always be listed.

3.8.6: The Committee shall move a nomination from another category to the work’s default category only if the member has made fewer than five (5) nominations in the default category.

3.8.7: If a work receives a nomination in its default category, and if the Committee relocates the work under its authority under subsection 3.2.9 or 3.2.10, the Committee shall count the nomination even if the member already has made five (5) nominations in the more-appropriate category.

I... don't actually know what all that means. Clause 3.8.4 seems to indicate that putting MoR up into multiple award categories would have the effect of splitting and diluting all votes, which seems like a bad thing.