Thanks Ali. As you say, there are births to John and Ann Mulliner stretching from 1803 - actually to 1822, or even 1826. It's not impossible they were all to the same couple, though if so I feel sorry for Ann who must have been carrying children around for most of 20 years or so.
But there is at least one, maybe two, marriages that might fit the idea of two or more sets of parents named John and Ann Mulliner. John and Ann Littler were married in Acton, not Audlem and, although it's still South Cheshire, subsequent birthplaces point to baptisms at Wybunbury or Audlem.
A John married Ann Harvey (also known as Nancey) in 1804 in Audlem, but their family is fairly well documented later so I have ruled them out.
But there is also John to Ann Hayward in Audlem on 1.8.1813 and that was my original assumption until I found the earlier births.
Hence my enquiry to see if anyone else had information to sort this out. I'll continue to ponder, but you have certainly given me food for thought - thanks