Testing out an ads-plugin -- Linker error (beginner's question)

Hi I am very new to Corona Enterprise and I am trying to build a test provider plugin in iOS.  I have taken Chartboost SDK as an example (simply because I am familiar with their documentation) and simply added all the frameworks required to the template plugin project provided, I have also changed the name of the plugin and, finally, I have added one “API” (called sessionStart).  I got an error in the linking stage that I cannot decrypt:

***

duplicate symbol _crypto_hashblocks_sha256_ref in:

    /Users/XXX/Library/Developer/Xcode/DerivedData/AdsTestApp-YYY/Build/Products/Debug-iphonesimulator/libads-myprovider.a(blocks-8650088D6BADC271.o)

[+ two more of these]

ld: 3 duplicate symbols for architecture i386

clang: error: linker command failed with exit code 1 (use -v to see invocation)

***

Q1 – What could generate that error (besides my incompetence that is)?

Q2 – I think it has something to so with linking frameworks in a plugin.  IF that is the problem, then I am not sure how a third party iOS SDK could be implemented.  But I could be totally wrong of course.

Thanks in advance for helping.