[Proj] Problem with merc projection

[Antonio Volpicelli]

Hi guys,
I am not sure that this is a right mailing list but probably someone can 
addressing me in the right place.
I am using the Mike Adair proj4js and merc.js code .
The trasformation using cs2cs gives me different result if I use the 
Mike code.
When I transform lon/lat to X/Y the Mike code give me a latitude lower 
then the cs2cs of about 0.200 degrees.
>cs2cs +proj=latlong +to +proj=merc
10.6846908 41.26904150
1189414.34      5023915.99 0.00

with the Mike code

1189414.34   5052106.58

Is there someone that has the same problem?
Help will be welcome and appreciated

Antonio