Is the this function executed twice?

Is the this function executed twice?

In the code below:
select t.id, ST_AsText(t.geom) AS tgeom, s.name,
ST_Length(ST_ShortestLine(t.geom,s.geom)) AS short,t.par
from teta t, str_lines s
Where ST_Length(ST_ShortestLine(t.geom,s.geom))<200
Is ST_Length(ST_ShortestLine(t.geom,s.geom)) executed twice ?