hi can any one advise me re do new fire doors have to have 2 spy holes - one for normal height & one for wheelchair users

I would advise you to consult Part M of the Building Regulations with regard to requirements for spy-viewers for wheelchair users.  

Fire performance tests have been conducted with more than one spy-viewer installed in one fire door leaf, but you should check with the company that manufactured the fire door before carrying out any installation work.

Edited April 17, 20197 yr by Neil Ashdown CertFDI
To provide additional information

Spy holes are a security matter, not a fire safety matter unless you are talking about vision panels? 

The fire safety guidance says if you are going to fit a spy viewer it has to meet a certain standard to ensure it does not compromise the fire resistance of the fire door and that is why I say it is a security matter. It doesn't say, you need eye viewers and certainly not how many.