The node name of an asset may not contain its file extension:

• the assets node name was changed by the editor (action 'Rename item')
• it's an 'old' asset (in older magnolia versions uploaded assets used not to have their file extension in the node name)

When duplicating such assets, they break, as the jcr property 'name' and the jcr content property 'fileName' both seem to get the node name of the original asset (added by a random number) instead of the value of their respective properties in the original asset.

An example using an asset on the public magnolia demo instance is attached.