Combustion air vents

I found 2 combustion air vents in the furnace area the other day, The end of one was higher than the other. Looked proper. Cold air was coming in both vents - not what I usually see. Found out the didn’t come from the attic like I normally find, they were getting air from under the deck. Is this proper??

Idealy you want one 12" from top of room and one 12" from floor. How far apart are these 2. Photo?
Hope this link works. Explains it with fotos

Pg 1. Figure 2.

Hi Chris, gone all weekend
1 was about 12 in from floor, the other was probably 4 ft from the floor. couldn’t get the pic to attach

I would say thats ok. As ling as there is an upper and lower vent to have proper air flow and pressure throughout the room.
“Appears to have a lower and upper vent to assist in providing the furnace room with proper amount of combustion air. Recommend during annual maintenance from a a licensed HVAC professional, to have them review the current design to ensure enough combustion air is present, since the amount is based on a mathematical equation of size and air ratio, which exceeds the knowledge and standards if a home inspection”

link wouldn’t open Chris