Can we decode twice in the same session with unarchiver?

In a class, I call the following (edited to simplify, but it matches the real case).

If I do this:

func getData() -> someClass? {

    _ = someURL.startAccessingSecurityScopedResource()  

    if let data = NSData(contentsOf: someURL as URL) {
        do {
            let unarchiver = try NSKeyedUnarchiver(forReadingFrom: data as Data)
            print((unarchiver.decodeObject(of: [NSArray.self, someClass.self /* and few others*/], forKey: oneKey) as? someClass)?.aProperty)

            if let result = unarchiver.decodeObject(of: [NSArray.self, someClass.self /* same other types*/], forKey: oneKey) as? someClass { 
                unarchiver.finishDecoding()
                print("unarchived success")
                return result
            } else {
                unarchiver.finishDecoding() 
                print("unarchiving failed")
                return someClass() 
            }
        }
        catch {
            return nil
        }
}

I get a failure on log : unarchiving failed

But if I comment out the print(unarchiver.decodeObject) - line 8, it works and I get unarchived success

            // print((unarchiver.decodeObject(of: [NSArray.self, someClass.self /* and few others*/], forKey: oneKey) as? someClass)?.aProperty)

However, when I do exactly the same for another class (I've compared line by line to be sure), it works even with the print statement.

What could be happening here ?