Unfortunately, this isn't an accurate description of the nature of the collision problem with MD5, which involves carefully crafted inputs using a sophisticated cryptographic attack -- not arbitrary user inputs that don't intend to collide with each other. See my and danielweber's comments about this down-thread.

(Yes, susceptibility to collisions was recognized as a problem with MD5 leading to a reason not to use it, but the collisions in question were constructed, not encountered accidentally. There isn't any evidence to date that the probability of a collision given two randomly chosen inputs is higher than the expected 1/2¹²⁸. You could test this yourself by hashing 2⁴⁰ random strings under MD5: you won't see a collision among the outputs!)