I have never seen a pick up tube with more than 1 Oring. Maybe a previous owner doubled them up?
GM does not make lifters, have not made them in 30 years. Eaton does make Lifters, Top Line USA does make lifters at the HyLift plant, I have used both Eaton and Topline Hylift and they work as well as OEM. I have chosen not to use the Moresa brand from Mexico because 20 years ago they had bad quality, maybe today they are top notch. The China supplied lifters scare me also so I have not used them even though the low price is tempting. Just too much labor to change one if it fails.
BTW: I understand there are two companies using the TOPLine name, make sure you use the USA manufactured brand. Talk to local machine shops that build engines every month. They will have current information on what brands work today.