New Collector - Two Questions RE Obverse vs Reverse and counterfeit banknotes [solved]

1.  I have a few banknotes, mostly German, where I can't tell which side is Obverse and which is Reverse.  Are there guidelines for determining which is which.?  Also, a number of my smaller German banknotes are only printed on one side.

2.  I have three Russian Empire standard 5 Ruble notes from 1909, each of the three have identical serial numbers, those being YБ 427.  Does this mean they are probably counterfeit? 

Try here:

Guidelines for the Numista catalogue – Numista

2. They printed many millions on multiple occasions of these so they obviously aren't serial numbers but block numbers. So it is not uncommon to have the same block.

1. Generally, the obverse of a banknote is the side with serial numbers.

2. Regarding your Russian notes (1909) with numbers the same. 

These are post-1917 Soviet government issues - a series number rather than a serial number was used on them. 

What a nice and informative forum.

Thanks to all three of you.  I will mark thus as resolved