1. Under login I see 3 lines of the form com.apple.idms.prd etc, 2 of which are identified as revoked. Can I and should I delete the 2 revoked entries?

2. Under the category heading I see 1047 items listed, predominantly duplicates with no sub-entries:

2 entries "<key> public key no dates
<key> private key no dates

7 entries "Apple ID {a constant email address} key public key no dates
4 entries "Apple ID {a constant email address} key private key no dates
of the 4 above, the last 3 have a sub entry as follows
com.apple.idms.appleid.prd.{constant very long certificate number} certificate expiry dates,various 2017

The remaining (over 1000) entries are nearly identical, without sub-items and of the general form:
iMessage encryption key public key
private key
iMessage signing key public key
private key

I'm running El Capitan because Sierra was unusably unstable, and I wonder if there is anything for me to be concerned about in the information above.

Thanks

David