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Thank you all for the replies, Surprisingly the keywords in question are climbing back up in SERP's, Eventhough I still have no clear answer of what the cause could have been, I am happy to see the Search Visibility Score rise! Thanks

Hey Alex! Christy invited me to pop by. Your 2 businesses exist in two totally separate categories, in Google's eyes: 'Air Duct Cleaning Service' and 'Car Detailing', so provided that you meet the following requirements, you should have no problems with running 2 legally separate businesses, even if they are both being run out of your home: Have a separate phone number for each business that is always answered with the correct company name. Have separate websites for each, with completely unique content on them (no shared content). Do not interlink your sites in an attempt to cross promote them. Build a unique citation set for each. Don't try to piggyback one business onto the other in your local business listings. If you can meet all of the above requirements, you'll likely be best served by going with 2 unique businesses. If your categories were related (like Car Detailing and Car Wash) I'd be giving just the opposite advice, but as your two service types have nothing to do with one another, I vote for running two legally distinct companies. Hope this helps!

As long as you are sure the posts on your blog are no longer on your site, you should be fine posting the same content again and not have to worry about duplicate content.