Laptops that supports second internal hard drive ?

Which current Dell Latitude and Precision Mobiles laptops can be configured with multiple internal hard drives  (for example SSD local C and 1TB 7.2K HDD for local D) ?

Or can any current Dell lineup of laptops be easily modified to have a 2nd internal drive?  For example the Dell Latitude E6440 can have the optical bay removed, and replace it with a HDD caddy with an internal drive.

Thank you.