Automation fails when it has two fields with the same name/type, showing the error "Found multiple fields with the same name and type:"

Issue Summary

Automation fails when has two fields with the same name/type, showing the error "Found multiple fields with the same name and type:"

In case rule has custom filed of type cascading and another custom field with same name exist then rule fails with below error: 
"Additional fields contains invalid field(s) in 'update' or 'fields' section.
<field_name>"

Steps to Reproduce

1. Create a new number custom field in a Next-Gen project
2. Create a rule to copy the value from this field. Below, follows an example.
   
3. Set the rule scope for the Next-Gen project.
4. Under <instance>.atlassian.net/secure/admin/ViewCustomFields.jspa create a new number custom field with the same name.
5. Associated the "number" custom field to a classic project.
   

• Reload the rule, and then run the rule.
• Then will appear the error "Found multiple fields with the same name and type:"

Expected Results

When we set the scope of the rule to a Next-Gen project, it should not consider a classic custom field. 

Actual Results

Even the rule restricts to the Next-Gen project, appear the error "Found multiple fields with the same name and type:". The rule is considering a field with the same name and type, causing this error. 

Workaround

We can change the field name to a different one, and then the rule will run without error.