From Minecraft Wiki
February 23, 2011
Beta 1.3_01 was released to fix some of the bugs and crashes in Beta 1.3.
- Dependencies on Java 1.6 are gone
3 bugs fixed
- Fixed the recent issues on macOS in which the game would crash when "Singleplayer" button was clicked on
- Able to connect Client to Minecraft Server 1.3
- Fixed item duplication glitch