There is a variety of reasons for weights being sold as seconds:
1) The most common reason is that the weight did not quite come up to the standard. This applies to unlimited weights only. The policy for limited weights was to destroy sub-standard items. This implies that your second was not a limited design as such.
2) Standard shaped weights would not be "abandoned" during the hot work - and still finished to be sold as seconds. A sub-standard item produced for later cold work (facetting, engraving), however, could be abandoned at this stage, i.e. facetting or engraving would not be done. Have a look at "
Coquette" - this could happen even for designs which (completed) would be limited editions.
3) Trial designs, possibly leading to a modified version going into production, could also be sold as seconds.
The problem with abstract designs is that often similar features show up in different designs. When comparing an actual weight with a single (catalogue) image it is often extremely difficult to identify the design. Looking through
ScotlandsGlass can only be recommended, though - but keep in mind that this catalogue is far from complete (unfortunately for technical reasons no longer complemented).