direct dowload link with or without masterkey ?

Hello,

When a file is updated, the package ID remain the same but the masterkey is updated, right ?

The direct download link is also different due this new masterkey.

Do we have to modified all links in our webpages, emails, documents, etc (lot of work and potential errors) ?
Or can we keep the initial direct download link ?

We noticed that a previous direct download link (with an obsolete masterkey) still gives access to the updated file.
So we would like to know this is a bug or will it remain active ?

We also noticed that the following link works
– http://www.xxxx.xxx/download/document/?wpdmdl=4142&masterkey=570880f552a9e
http://www.xxxx.xxx/download/document/?wpdmdl=4142

Is the masterkey useful in direct links ?

Thank you in advance for your support

Fred