Writers use pen manes for various reasons, some to hide their identity and others to try to write in a style that society wouldn't permit such as Robin Hobb http://www.robinhobb.com/novels/, or George Eliot http://www.bbc.co.uk/history/historic_figures/eliot_george.shtml.
For my sake, I wrote under various names that I thought would suit a genre, this lead P.A. Canella to write Science Fiction https://www.draft2digital.com/book/32495 / Lana Pawcel to write erotica https://www.draft2digital.com/book/32234 / Al Place was the name I wrote crime stories under https://www.draft2digital.com/book/32325. In the beginning I used my name Alan Place for general stories https://www.draft2digital.com/book/34522, I returned to using my name recently for ease on Amazon, not that it made a difference as sales never picked up which is why my books are only for sale on Draft2Digital.
As a note to end on, as my only success story is the Forgestriker series http://alsdomain.weebly.com/forgestriker---the-hit-series.html, I decided to return to using my pen name of P.A. Canella.