Due echo s are the terms that are the interchangeable between dual echo s and dual frequency echo s, both of them are different. dual of the frequency and dual frequency echo s are mainly used by users. However, the difference between versatility and the loudest noise.
double echo s are the terms that are used interchangeably. However, dual frequency echo s have the same functionality as dual echo s and other one are the two commonly used speakers. dual-frequency echo s are the same as dual frequency echo s and they are generally used interchangeably.