Liberia, ca 1890-Slave State?

I was talking to an african friend(he is from Ghana), who told me that the country of Liberia was settled by ex-USA slaves. After the American Civil war, the USA paid for ex-slaves transport to liberia, where these people set up a republic. only, by 1890 or so, they had recreated the pre-Civil war plantation South! They did this by enslaving the local people, and set up rubber, coffee, and indigo plantations.
My question: why would people who had suffered under slavery themselves, set up the same system?
At any rate, the ex-slaves, now plantation owners had big white houses and lived lavish lifestyles. All of this came to en end (in the bloody revolution of the 1980’s)-the native people booted out the overlords.
So, was liberia (for the local people) as bad as the antebellum south was (for african-americans)?

I don’t believe it was officially a slave state. I think it was run as a typical African colony of the period with the exception that instead of white Europeans exploiting the natives, you had black Americans doing it. So you had a system where the colonizers owned all the land and businesses and also wrote and enforced all the laws - a system ripe for abuse of the native population.

Slavery was outlawed in Liberia in 1931, after a League of Nations investigation, at the behest of the Liberian government, unearthed slavery, forced labor, and actions by the Liberian Frontier Force (the Liberian army) of forcibly recruiting workers and selling them to the Spanish island of Fernando Po and the French colony of Gabon.

As this Time magazine article points out, the report notes:

http://www.time.com/time/magazine/article/0,9171,740880,00.html?iid=chix-sphere

As to why people who had suffered under slavery would set up a slave system themselves, that’s pretty obvious, isn’t it? They’re no longer suffering from slavery, but are in a position to benefit from it.