Searching Contacts from 850 Companies: Enrichment Tools and Duplication Avoidance

Hey - I've got a list of 850 companies from Ocean.io. I did a "Find more people from these companies" native enrichment, and found 352 contacts that were inputted into a new table. What's the best way that I can still search for contacts at the remainder of the 850 companies, using other enrichment tools (clear bit, apollo, find contacts at companies etc) and avoid duplicates I'm guessing it's something to do with "Look up rows". Would it be something along the lines of going to the original company table of 850, and doing enrichments in there with other tools, and using the look-up function to not run if the domain is found in my other table? How would this work