You could certainly do something like
is ( equal( lhs(eq1)-rhs(eq1) , lhs(eq2)-rhs(eq2) ) )
as you suggest, but that does NOT test that the truth-values of the
equations are the same.
After all, 2*x=0 and x=0 are equivalent equations, but 2*x is not equal to
x. Logically, what you want is something like
is ( equal( zerop(lhs(eq1)-rhs(eq1)) , zerop(
lhs(eq2)-rhs(eq2) ) ) )
but Maxima doesn't support any such zerop function.
You could define zerop(q) := signum(q)^2 , which is perfectly correct, but
the <is> system won't be able to do anything useful with that.
-s