As stated in Wiki, it is quite rare for a secondary rainbow to occur. When it does, the second rainbow is usually fainter, which usually locate outside the primary one. Because it is a reflection of the primary one, the colours are usually in opposite order of the primary rainbow i.e. violet on the outside and red on the inside!
Click here to read my earlier post about two rainbows appearing in the sky – I considered it an auspicious sign !
Ps: There are quite a few photos of it !