Was Cui really as strong as Vegeta?

It's commonly accepted that Cui had a power level of 18,000, which is the same power level as Vegeta during the Saiyan Saga. But re-reading the manga, this isn't really accurate. Frieza says Cui is stronger. Cui himself says at one point that they're equal, but then seems surprised when Vegeta's power matches his.

Dodoria says Vegeta's power level should be at 18,000 based on the last time we saw him. When Vegeta is charging up though, Cui says his power is higher than his -- but then lists of 19,000 and up. Maybe Cui was stronger prior to the Saiyan saga, but just by a little bit?

Is this just some strange translation issue?

It does feel weird that someone like Cui would challenge Vegeta 1 on 1 if his power level was only a couple hundred higher than Vegeta.