Everyone I ever meet thinks I look like someone they know. I probably have enough doppelgangers to populate a small town of Finn lookalikes.
Let's see your coins and their doppelgangers!
I'll leave it somewhat open to interpretation, but the coins should share some uncanny resemblance without being *directly* related. I'll illustrate with a few examples from my own collection:
Similar fabric:
Chunky, thick ovoid silver weighing about 4-5 grams:

Left: Achaemenid siglos, around the time of Xerxes I, ca. 480 BC
Middle: India, "Sri Omkara" drachm, used perhaps to pay the workers at the monastery of the same name. Ca. 1300 AD.
Right: Japan, Mameita Gin, Tenpo era, or about 1830.
Same imagery, different meaning:
The infamous Swastika

Left: Bronze "drachm" from the Silk Road city-state of Chach, AKA Tashkent, ca. 600 AD. Swastika is assumed to indicate Buddhist affinity.
Right: Third Reich 50 pfennig 1941. A very different Swastika that ruined the ancient good luck charm for everyone.
Cultural continuity:
The script used more than 2,000 years apart

Left: China, "Ban Liang" in seal script, meaning the coin weighs 1/2 liang, or Tael. Cast in 3rd century BC.
Right: Japan, Ryukyu islands, "Han Shu" in seal script, meaning 1/2 shu, or 125 mon. Cast in late 1860s.
Let's see your coins and their doppelgangers!