5.0.0 versus 5.1.0 theme

The theme that came with a fresh 5.1.0 64 bit download didn't suit me, so I reinstalled 5.0.0, to keep the MokshaGreen theme available to 5.0.0.

Would there be a way to change theme in 5.1.0?

Thanks

Add: did add a theme via synaptic that resembled MokshaGreen, but it ended being a mix of both.