On the surface, one might expect that two similar, if not almost identical, rifles would exhibit very similar tuned loads if using the exact same reloading components. That seems like a very reasonable conclusion to make, right up until you encounter two similar rifles for which the tune is noticeably different. It is difficult enough to anticipate with any great accuracy the effects of reloading component Lot-to-Lot variance such as powder burn rates, case volume, etc., let alone the potential differences between two barrels. Because we can empirically tune a given rifle and the fact that one individual will usually be consistent with their selected tuning approach from rifle to rifle, the best bet is simply to determine what the rifle wants for an optimized load. If that load happens to be the same as an optimized load for a similar rifle, great. If not, it won't matter because the two rifles were each tuned individually. If the idea is to use someone else's developed load for a similar rifle as a starting point for your own load development, there is nothing wrong with that as it can save time, barrel life, and reloading components. But you want to be aware that it is only a starting point, and you still need to cover charge weight and seating depth windows that are sufficiently wide, especially if re-creating the exact same load doesn't seem to work as well as it did in the other rifle.
I've had multiple barrels on at least three different rifles set up very similarly where the charge weight and seating depths for each have ended up very close over a period of several years, meaning with different Lot#s of powder, bullets, and brass (each from the same manufacturer, i.e. Varget/Berger/Lapua). So it certainly can happen. Likewise, if you look around at what F-TR shooters are commonly using in .308 Win, you will find that many of their loads are almost superimposable. For example, the use of a 30" barrel, Varget, 200.20X bullet, Lapua brass, yielding ~2640-2660 fps is a common recipe for success in F-TR. But it's not written in stone that it has to be that way. Variance in powder burn rate, effective case volume, or even bullet diameter can cause noticeable changes to have to be made to optimize a given load. The less stringent the precision requirement, the more often it will likely be that the same load appears to work well in two very similar rifles. If you're striving for the utmost in precision, it may be more noticeable that subtle, or even not-so-subtle changes in the load are necessary to get two similar rifles shooting optimally.
