Due to their reputation/popularity, there are many FAKE British Dragon products going around. This includes underdosed products or products that do not contain the proper steroid (i.e. Test Cyp instead of Primo). Some fake manufacturers will replace the real stuff with something else (a crimper is only 150 dollars) and no one ever finds out until their products get tested.
The only real way to know if your stuff is NOT fake, and is the real stuff from British Dragon is to go to the
British Dragon Supplier Checker and enter the domain/name/email/whatever of the source you use. OR, like PC said, "know your source''. Make sure they aren't removing the good stuff and replacing it with something you don't want, etc.
The proper BD stuff is good, the fakes are bad--look around on other boards and you'll find plenty of evidence confirming my assertations.
Secondly, both the British Dragon OT and DBOL are very similar in appearance, both are small, square pinkish/purple tabs. And to make it even more difficult to discern the two, BD tabs vary slightly depending on which one of the two factories produce them (some tabs are thinner/lighter colored than others of the same type).