Aylesbury and Aylesford - I've known those two to be confused with each other in the past.
There's a Sainsbury's Supermarket in Aylesford, Aylesford is a postal town and the supermarket lies within the parish's boundaries as well but the receipts and the website describe it as being in Larkfield, two villages along the London Road. When I enquired about this many years ago, they said it was because they didn't want to confuse it with Aylesbury.
Of course, Larkfield is in the postal town of Aylesford, which rather negates the point.
Many times as a student, I'd tell people I came from Maidstone, and they'd confuse it with Maidenhead. And my wife once advised a friend who was moving to Langley (Berks) to chat to me because I had family from King's Langley (Herts).
Tangentially related to the railways, within about 40 miles of one another in northern Lincolnshire are two villages called Ulceby. One has a train station, the other doesn't, and it's nigh on impossible to get from one to the other by public transport if you choose the wrong one. In fact, sadly, a young man died after a night out in Cleethorpes because it is alleged he realised a taxi driver was taking him to the wrong Ulceby, so he got out to return to Cleethorpes only to drown in a ditch while walking back.