Already connected Rail reconnect to a new rail next to it.

Try building the same rail structure but at 90 degrees to the angle you set up (I.e. if the rail you just tried runs east-west, try it north-south). You should also take a look at rail placement behavior: http://minecraft.gamepedia.com/Rails#Placement:

When placed, a rail will configure itself to be straight or curved according to rail blocks around it.

• If there are no other rails adjacent it will be placed as a straight track oriented north-south.

• If placed at the end of an existing stretch of track, the new rail will be a straight track section oriented to continue the existing track, either east-west or north-south.

• If placed beside an existing stretch of track (of any type) the newly placed rail will be straight and oriented north-south.

• If there are two adjacent rails on its level, or one level up or down, the newly placed rail will configure itself to connect the other two. This means that it will be placed as a straight or curved track as needed.

• If placed between three adjacent rails (thus always forming a T-junction) the newly placed rail will be placed as a curved track south-to-east, north-to-east, or south-to-west to join those sides.

Does this bug still appear in 0.13.1? If so please respond.

Fixed in 0.15.10. Also tested in 0.15.90.8. Probably fixed in a much earlier version.

Looks like this same bug has popped up again in 1.16.100.51 beta