Norseman corrosion

[conachair]

I recently replaced all the standing rigging with dyform, keeping the original norseman fittings but replacing the wedges. A delivery error meant the wedges came from 2 different sources, first ones now look like this

but second batch look like this. Doesn't show up great on photo but there's a little rust seeping from the fitting.

Any pointers as to what might be going on? Doesn't look right . Looks like maybe galvanic corrosion but I thought norseman were only available in stainless.
Thanks in advance