You Do Need power plug adapter while traveling from Namibia to Lebanon.

Here is Why You Need An Adapter

The outlet and plug type used in Lebanon are C, D and G and in Namibia are D and M. This is how they look like.

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M

Lebanon

In Lebanon, outlets of type C, D and G are in use.

Type C

Type D

Type G