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

Here is Why You Need An Adapter

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

Seychelles

In Seychelles, outlets of type G are in use.

Type G

Namibia

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

Type D

Type M