Think about the merciless teasing at school & then also sometimes later in the work place,
If you were called "DUDLEY" & it was shortened to "DUD" you might get fed up at always being the dud or useless one!!.
When you moved house or changed job you might swop names around or even use another one already in the family, to avoid a repetition. It wouldnt worry me, as I have had many different variation used on my name when changing locations. But some could get very upset, and, & some people can be very irritating in this respect.
Another example is if your called "DONALD" & people started singing/humming "Old McDonald had a Farm" every time they saw you.
Or even if there was a local infamous person with the same or similar name, you might want to change.
Besides I expect that by the 1940-50s the Victorian ethics were begining to loose their grip on people