Why random works like this in Ruby?

I was trying to be clever about deterministically picking random stuff and found this:

irb(main):011:0> Random.new(Random.new(1).rand + 1).rand == Random.new(1).rand
=> true
irb(main):012:0> Random.new(Random.new(5).rand + 1).rand == Random.new(5).rand
=> false
irb(main):013:0> Random.new(Random.new(5).rand + 5).rand == Random.new(5).rand
=> true

For a second I thought "wow maybe that's a property of random number generators" but Python and C# fail to reproduce this.