they’re fundamentally the same chip. iclass SR is iclass legacy + SIO blob with standard keying
TLDR: has CSN unique fingerprinting, can be sidestepped if legacy is enabled on the reader (bear in mind HID has recently been making a big push for clients to disable legacy when not needed so YMMV)
Fluffing out the above: when your reader identifies your card and sees it is configured as SR, it will attempt to match its SIO & CSN & PACs to what it knows, your SIO on the cloned card does not match the CSN it belongs to since you can’t change CSNs on standard iclass.
when it sees your SR fail the SIO, it rejects. making the credential legacy & relying on the reader having legacy enabled means the reader only looks at the PACs (facility code & card number) and doesn’t bother to check for the SIO.