Indirect + direct object pronouns

Question

For the phrase: Van (Uds.) a enviar los premios a nosotros?

To answer this question negatively, would it become:

no nos vamos a enviarlos

no nos los vamos a enviarlos (does the combination of nos + los clash because of the similar sounds)

Thank you!

Answer

The question means - Are you going to send the prizes to us?

To answer negatively you would use the pronoun you in the plural not nos.

No, we are not going to send them to you.

No, no vamos a enviárselos.

Answer

Hola Scarlett 
As Marsha said, you'd need "No, no vamos a enviárselos." or you could also place the pronouns at the very beginning and detatched from the verb:  "No, no se los vamos a enviar." 
If you use the you informal plural (used in Spain, not in Latin America) "vosotros", then the "se" becomes "os", so you'd say:
"No, no vamos a enviaroslos" or "No, no os los vamos a enviar."
Saludos
Inma