I am wondering if it would help to have multiple inbound links from different pages on the same domain. Would it be less effective as inbound links from separate domains... or the same?
Yes, it will help. Google will downgrade the links slightly but overall your site will get the 'credit' for it.
If the site giving you sitewide links is pertinent to your topic and autorithative, it's will be better than multiples links from 'bad neighbourhood'. But it's would be even better to get one link from many related and trusted sites
We should always try to get links from the main website which is getting backlinks from many related websites. Its like if there are 5 websites linking to 1 Website. You should prefer that 1 Website. Since, its interlinking you to those 5 websites related to your niche also. Thats what true link building with human intelligence, can be known.