Order numbers

-- HikaShop version -- : 3.2.2
-- Joomla version -- : 3.8.3
-- PHP version -- : 7

Hi

I am using formats:
Order numbers {id size="5"} /{date format="y"}
Invoice numbers RE-{id size="5"} /{date format="y"}

But why do I get order IDs / order numbers only every second like
00006 /18
00008 /18
00010 /18
00012 /18

What about the numbers in between (7,9,11...)?
Is this as it should be or a wrong setting by myself? Or something to do with Hikamarket?
Invoice numbers seem to be normal consecutively 1..2..3..4..

Thanks