Unusual middle names. Any ideas of why?

[Marmalady]

One of my ancestors in the early/mid 1800s seems to have been an early genealogy enthusiast -- he revived several earlier maiden surnames as names for his children --  some of which were then used for several more generations. So even tho Trant is a rare surname there are several unconnected family groups but whenever I come across a "Baron Trant" or a "Beverley Trant" I know they are one of mine! One branch in the USA still use the name Beverl(e)y for the eldest son today but had no idea where it had come from, only that it was a family name. (Elizabeth Beverley married Thomas Trant back in 1803!)

[Pennines]

Whilst researching an in-laws family tree for them - I came across a non-conformist baptism where the child had been given the preacher's forname and surname as 2 middle names. (I can't remember the religion now).

[Heritagefound]

Thank you everyone for your answers.  I have considered that they could have been in-law or ancestors names etc, but I can see no link. I have often come across the mothers maiden name as a middle name though, and famous national figures such as Nelson for example.
So I can only think, as suggested above, that these must of been family friends surnames, although you would think it would be a first name as today. But fashions come and go with naming.
Yes Simpson was Martha's maiden name, but is found used as a middle name too.

[gaffy]

It doesn't always have to be a relative, in the context of Northern Ireland, I have encountered 'Carson' given as a middle name in several instances (from Edward Carson), also in the military context, middle names like 'Kitchener' and 'Haig'.

I've also encountered the surname 'Wesley' incorporated as a middle name in Methodist families.
 

[gaffy]

I've also encountered the surname 'Wesley'  incorporated as a middle name in Methodist families.

And in one instance the middle names 'Charles Wesley'.

[bikermickau]

I had 1st cousins 3 times removed in Scotland, Jane Ralph Henderson and Mary Dorans Henderson.
Ralph was their maternal Grandmothers maiden surname and Dorans was their maternal Grandfather surname.

[Rena]

One of my OH's ancestors had a very large number of children and after they had completed the old fashioned naming pattern I recognised the names of further children as originally belonging to childhood friends and neighbour s of the wife.  The neighbour that stood out was the child who held the name of the sea captain who had lived next door to the child's mother when she was young..I hazard a guess that the wife had the final say in naming the couple's children lol 

[Lola5]

Yes middle names were often family surnames.
Eg John Burley Coleman...his mother  a Burley who wed a Coleman.
And my great grandmother named her daughter Amelia Sarah  Amy Rippengal Linnett.
So useful in identifying my great great grandmother.( Amy Rippengal.)
Others even  had middle names named after battles!

[Pennines]

Gaffy --one of my own Methodist ancestors named John Crabtree -- registered and baptised by that name - later became John Wesley Crabtree. He must have added that middle name later, himself.