Why is this an issue?

Using multiple times same the name for different signals is confusing. Names should be unique and should describe the functionality.

How to fix it

Code examples

Noncompliant code example

File 1:
entity e1 is
  signal fly : type1;
end;

File 2:
entity e2 is
  signal fly : type1;
end;

Compliant solution

File 1:
entity e1 is
  signal fly : type1;
end;

File 2:
entity e2 is
  signal dream : type1;
end;