es-link1.frag
Shader version: 100
0:? Sequence
0:5  Function Definition: main( (global void)
0:5    Function Parameters: 
0:7    Sequence
0:7      move second child to first child (temp mediump 4-component vector of float)
0:7        'gl_FragColor' (fragColor mediump 4-component vector of float FragColor)
0:7        Function Call: calculateColor( (global mediump 4-component vector of float)
0:?   Linker Objects

es-link2.frag
Shader version: 100
0:? Sequence
0:5  Function Definition: calculateColor( (global mediump 4-component vector of float)
0:5    Function Parameters: 
0:7    Sequence
0:7      Branch: Return with expression
0:7        vector-scale (temp mediump 4-component vector of float)
0:7          'varyingColor' (smooth in mediump 4-component vector of float)
0:7          Constant:
0:7            0.500000
0:?   Linker Objects
0:?     'varyingColor' (smooth in mediump 4-component vector of float)

ERROR: Cannot attach multiple ES shaders of the same type to a single program