Two modules are equal if they are isomorphic as subquotients of the same ambient free module.
i1 : R = ZZ/101[x] o1 = R o1 : PolynomialRing
i2 : image matrix {{2,x},{1,5}} == R^2 o2 = false
i3 : image matrix {{2,x},{0,5}} == R^2 o3 = true
