So a lot of companies outsource to India for their background checks and the two parties don't really communicate very well. So in several instances I've given my resume which says one thing. The last one even said I had a bachelor's degree (I don't). Get an offer based on that.
Then you get a link to give information to the third party company. They usually want you to manually enter your information into their system, so they don't really want or look at your resume. So when you input the info, give them the correct information. They double check that and pass you, neither party is ever the wiser.
The last 3rd party background check company (if you heard the name, you'd recognize it) was so bad. One of the items I gave them was that I was self employed for the last 7 years, which was the truth. I put in my own info as the employer, they even had a drop-down for type of employment. I checked “self-employed” and they actually called me to verify my employment. I tried to explain their error to them twice and they didn't understand what I was trying to tell them. So I just ended up lying, saying that I was in fact my own manager and verified the dates.
You get what you pay for?