EXCLUSIVE: Sylvester Stallone's Signed Memoir Sparks Autopen Mystery as Fans Spot Five Different Signatures

The online discussion has also exposed disagreement about what constitutes suspicious variation in a celebrity's handwriting.

Stallone has spent decades signing memorabilia, and experts say autograph styles can change considerably depending on speed, writing position, fatigue, and the number of items being signed.

One autograph hunter's research has nevertheless uncovered distinct patterns across commercially distributed copies of Stallone's memoir.

In one update, the collector reported examining 102 examples of Stallone's signatures, dividing them into five groups containing 10, 16, 36, 20 and 20 signatures.

Among the 28 British examples, two styles accounted for 24 signatures, suggesting certain variations may be concentrated within particular distribution batches.

The figures represent the collector's observations, not an independent authentication study.

The controversy is particularly sensitive because signed celebrity memoirs have become desirable collectibles, with purchasers often expecting a personal connection to the performer whose name appears inside.

An autograph hunter told us: "What's caught people's attention isn't simply that Sylvester's signatures look different. It's that collectors believe they've identified five fairly distinct styles appearing across books that were all marketed as personally signed.

"Anyone familiar with celebrity autographs knows signatures can evolve, particularly when somebody is signing hundreds of items in a single sitting.

"But when you start seeing recurring patterns that appear to fall into separate groups, collectors naturally want to understand why."

"That doesn't establish that anybody else signed these books or that a machine was involved," he continued. "What it does establish is that buyers have questions they would like answered, and those questions are becoming increasingly difficult to ignore."

An autopen, which mechanically reproduces a stored signature, can create convincing inscriptions without the named individual physically signing each item.

Secretarial signatures involve another person writing the celebrity's name, while ghost-signing similarly raises questions about who actually held the pen.

However, differences between signatures alone cannot establish that any of these practices occurred.

Stallone's book chronicles his difficult beginnings, including financial hardship and the extraordinary journey that eventually produced Rocky, the boxing drama that transformed his career.

Collectors are continuing to compare newly delivered copies and share photographs of signatures they consider unusual.

One participant also posted footage apparently showing Stallone signing books in London, adding another reference point for examining his handwriting.

The online comparisons have not established wrongdoing by Stallone, his publisher, or retailers, and no forensic examination confirming mechanical reproduction has been presented.