Using the same Apple iCloud with 2 devices I am going on holiday and want to use my second iPhone with a local SIM card.  So I want to know whether I can configure the second iPhone using the same apple account or if I should rather create a new apple icloud account?

iPhone 5s - my UK sim card associated with my iCloud account
iPhone 4 - SA sim card - rebuild and synced with my iCloud account

Then use both phones while on holiday.

Any thoughts?
Using the same iCloud account on both phones shouldn't lead to any issues. After all it's basically the same setup as using an iPhone and an iPad with the same iCloud account, and that's something which works for a lot of people.