Expat Medical Insurance

I am an Instrument Construction/Completion supervisor for petro chemical plants. I have worked in China, Russia, Saudi, Abu Dhabi and Qatar.

After I recently applied for a job, I got offered a position in Nigeria. The job offer requested me to get my own expat insurance from any company in Nigeria. The choice of this insurance company was up to me, but the job-offering company proposed an insurance company that they normally deal with. Is this a normal request?

On all my previous jobs, this was not requested from me as the company that hired me, would pay for this insurance. However, I always had to pay for my medical examinations and visas in my home country, which were than refunded when I start working abroad.

If somebody can advice