Singer centenary models; just wondering
So, one singer treadle and 3x99k"s (one a foot pedal, one a knee lever and one a handcrank) later I'm thinking I need to build on another room. The kitchen table is now the sewing machine operating theatre and the dining nook has become the Singer Nook...piffed that dining table right outta there! Have got the 1917 treadle going and tidied up and am now starting on the 99k's.
Can anyone tell me why there are Singers' badged with the centenary badge yet are, according to their serial numbers made in 1950, not 51?