_check_load_attr is not checking for duplicate full_name

[kilimchoi]

I got an error message like below,
Could not execute command: Could not determine attribute to load. Options: ['boa.interop.Neo.Transaction.GetReferences', 'boa.interop.Neo.Transaction.GetReferences', 'boa.interop.Neo.Transaction.GetReferences', 'boa.interop.Neo.Transaction.GetReferences']

I dug deeper into it and found out that it could not determine attribute to load when I called tx.References where tx was GetScriptContainer.

I made a check for duplicate full_name in the _check_load_attr in expression.py which resolved the problem.

[localhuman]

Thanks for the bug report! Will look into it-