In Israel there are many names that are unisex; used for both men and women. What is the halacha regarding using a traditionally boys name for a girl and vice versa with regards to writing those names on the ketubah?
For example, Daniel and Danielle are both spelled דניאל in Hebrew. I came across this exact issues which was apparently resolved by writing the female version as דניעל. I'm unsure if this is particular to the name דניאל which is a male Jewish prophet but I could imagine such an issue arising with other Tanach names, of men or women, being used in modern times for the opposite sex. Given that such a change was made I imagine that a normal rendering of the name may invalidate the ketubah somehow?
What is the halacha regarding this?
In a related question: if two people have the same non-Tanach name (e.g. both Maayan or both Ori or both Shachar etc. which are unisex*), does the exact same name go on the ketubah for the husband and wife in the situation that they both only have one name?
*Disclaimer: I've not checked whether these names are found in Tanach! Please edit accordingly.