Java Edition Infdev 20100321
From Minecraft Wiki
March 21, 2010
The fifth version of Minecraft Infdev was released on March 21, 2010.
- Duplicate login detection added, however it causes problems. (See Bugs for info)
- When playing the game, a screen will sometimes randomly pop up saying, "Session conflict! Did you log in from another computer?" It is unknown why this bug occurs.