CAA: Christian Anime Alliance

I recently finished watching this, and had started to watch the OVAs, but it looks like it's gonna be the exact same story, is there much extra/different to the OVAs at all that would make them worth watching?

The original series is based off the manga and then invents a new storyline after a while. The OVAs have so far followed the manga more exactly (and Hellsing is nearing its end, so it seems likely to continue). In my opinion the quality of the OVA series is better, but there will be a few episodes with basically the same plot, so it's your call.