True, do we ever have a datapoint where a legacy attraction (in bones at least) was identically cloned? Space Mountain at HKDL - DL perhaps, but even that had been recently rebuilt.
Sure, it happens all the time, but it seems to occur most frequently with opening day attractions. Once parks are up and running, there tend to be some modifications to fit the space available
Most of TDL followed that approach when it opened; WDI's primary team was busy getting EPCOT Center open, so the B Squad cobbled together a park out of the "greatest hits" from DL and MK. There were some changes to the queues, but Pirates, Space, and Pinocchio (built concurrently) were direct copies from Anaheim, while Mansion, Peter Pan (with 2nd story load area to replicate the deep Utilidor-level show scenes), Snow White, and iasw (with new double-load station) were lifted from Orlando. The Jungle Cruise and Raceway are substantially similar to the MK versions and Rivers of the Far West and Tom Sawyer Island were nearly identical to DL's, with some minor tweaks. TDS copied DL's Indiana Jones Adventure (also copied for DAK's CTX), but I'm not sure if enough time had passed to be considered a "legacy attraction"
DLP's Phantom Manor is a direct copy of DL's Mansion layout, but with different scenery along the way. There are some minor modifications to the track layouts, but Pinocchio, Snow White, and Peter Pan are nearly identical to the Anaheim versions. WDSP's Rockin' Rollercoaster is a direct copy of WDW's track, though both are off the shelf layouts
When HKDL opened, Space was copied from DL and TDL, and Pooh was lifted from WDW. DL's Rivers of America layout was copied nearly identically for the Jungle Cruise, with some changes to the shorelines and scenery
There are also the various flat rides/spinners, rides that were developed concurrently (Buzz Lightyear Astro Blasters at DL, TDL, DLP, & HKDL; TOT at WDSP, DCA, & TDS; TSMM at DCA & WDW) or very close together (Big Thunder at DL & MK mirror image; Roger Rabbit at DL & TDL; Indy at DL & CTX at DAK), and other facilities and entire lands (Swiss Family Treehouse in various locations; MK's castle and Tomorrowland entry/promenade at TDL; DL's Village Haus & DLP's Au Chateau de la Marionette; DL's Main Street and castle at HKDL), but I don't think that's quite what you were going for