The record
On November 7, 2019, a user says Siri on their iPhone 8 began mixing up two contacts after a recent update, calling the second when asked for the first and the first when asked for the second. They report spelling the names aloud, and although Siri's transcription appeared correct, it still placed the call to the wrong person. No OS version is given, and a Community Specialist's suggestions did not lead to a confirmed fix before the thread closed. This is a single user's report and should not be generalized.
Read the original source at Apple Support Community (opens in a new tab) ↗
A documented user report, not an independently reproduced test or an estimate of how often the problem occurs.