Constructing an IDP with metadata string reads certificate of both IDP and SP

[FreifeldRoyi]

When given a metadata xml with both IDP and SPSSODescriptor, it takes public certificate of both instead of taking just the one relevant to the constructed object, e.g:

const metadata = '...<SPSSODescriptor ...> ... </SPSSODescriptor>.. <IDPSSODescriptor ...>... </IDPSSODescriptor>'
const idp = IdentityProvider({metadata})
const md = idp.entityMeta.getX509Certificate('signing') // will return 2 certificates