In the past few weeks we have had back to back fixes which have been pushed to live, hence the notifications. The File which you are downloading is the Adobe Download Manager file which manages the Adobe Flash Player download and Installation.
What I can do i ask the product team which handles the ADM to look into this and provide with an answer to your query.
While the online installer file name is different, they do download the same version of Flash Player in the background. The difference is as follows:
- AdobeFlashPlayer_18_a_install - installer file downloaded from http://get.adobe.com/flashplayer
- AdobeFlashPlayer_18au_a_install - installer file downloaded from an update notification dialog window
As for the difference in File size, I do know the team that handles the online installer made a few changes to the file recently which may explain the difference in size.
Thanks for the clarification. I'm glad it was from Adobe. For future reference, is there any way to cross check and verify the authenticity of the disk image file? A MD5 hash or SHA-1 or something like that specified in Adobe's web site would help.