In theory, no.
For every major modern lens maker of which I am aware the optical formula stays the same for a given model. Sometimes, in fact, a new model is introduced with only cosmetic differences and the optical formula is identical to its predecessor (e.g. The Canon EF-S 55-250mm f/4-5.6 IS and EF-S 55-250mm f/4-5.6 IS II).
In practice? Well...
Two lenses with identical optical components may perform very differently if the optical elements have differences in the precision with which they are aligned. That's one reason many lenses have adjustments that are made at the factory after the lens is assembled and checked optically. Once the adjustment is made the adjusting screw is sometimes "sealed" with a drop of paint or glue. If the lens needs realignment later the "seal" can be broken. Sometimes with cheaper lenses the variation is considered acceptable by the manufacturer and no such adjustments are provided. There are lens collectors who seem to make an entire hobby out of testing multiple copies of such lower priced "budget performance" lens models until they find one that is well-aligned and matches their particular camera body.
As Roger Cicala discussed in great detail in a blog entry back in July, 2013, lens makers often include "silent updates" to non-optical components inside lenses. He used an example that had different circuit board designs in older and newer copies of the Canon EF 85mm f/1.8.
As someone who takes apart lenses and cameras for my day job, I did confirm to that person that over the lifespan of a lens, some internal changes may occur and the camera companies don’t make announcements about them. (I don’t like the term ‘silent upgrade’ because such changes aren’t always an upgrade, it may be something as simple as a new vendor supplying a slightly different part. There also seem to be times when the change is actually a downgrade.)
Suppliers of mechanical components may be changed due to quality control issues, budgeting, or a variety of other reasons that may have nothing to do with optical performance. Even when parts are from the same supplier, as tools used to produce parts wear the tolerances on the parts will vary. Some of those parts, while not directly affecting the optical formula, can affect how well those parts are aligned inside a lens when it leaves the factory and how well those parts stay aligned as the lens is subjected to the stresses of transport and usage. In another blog entry that discusses, among other things, why sometimes certain lenses seem to have "good" and "bad" batches Roger says this near the end:
We know every manufacturer outsources some of their parts, and the outsource suppliers are rarely known. I would assume that also means suppliers for all those metal parts that hold the lens elements in supposedly perfect positions put in bids and supply the parts to the manufacturer for later assembly. The subcontractor may change, the machine tools may wear out, and one batch of helicoids may be slightly different than another batch, or one set of circuit boards more prone to short out. Perhaps this explains why one batch of a given lens seems to have problems while other batches seem to do fine. It may also explain the much speculated “silent upgrade” event (when people claim that lenses that used to have a high problem rate, no longer do because the manufacturer supposedly did some kind of ‘silent upgrade’).
Earlier in the same blog entry he states:
While not studied, there has long been a lot of talk that certain lenses had “bad batches”, or that manufacturer’s made “silent upgrades” to certain lenses, improving quality. Certain Canon date codes on a few lenses are unpopular because people have reported lots of trouble with just that date code (no slam on Canon, at least they put a date code on their lenses). Other lenses are widely believed better if you get a later copy, the early ones had problems.
Our own experience supports this...
As the founder and chief lens guru of lensrentals.com Roger probably has as much experience with multiple copies of lenses from multiple production runs of the same model as anyone on the planet outside of a lens manufacturer's official service center.
So if the manufacturing process being used to produce the lenses isn't sufficient to result in lenses where the optical elements are lined up with each other within the manufacturer's required design tolerances, then changes to mechanical or electronic elements are sometimes made to correct the issue. If parts from a supplier fall outside the allowed tolerances the vendor may be required to retool and/or take other measures to correct the problem or another supplier may be found.