Yes, regardless of what start and end dates you put in for them, a result will always be returned. You can confirm this if you select 'No' in the "Date of Event Range" box, thus allowing you to put in a specific date. Any date in 1906 put in that box will return a match for Eric Plane or Dorothy Plane. Furthermore, you can confirm the 23/04/1907 death date by putting that in the box when searching for deaths for Eric. Nothing is returned if another date is entered.
It's a weird anomaly, and I don't know the reason for it. Just that a small percentage of BDM entries are affected by it, usually in the early 1900s [of course, most of the early church records on there, baptisms, e.g., will also give a result for any date, presumably because the birth date is not necessarily given on a baptism]. 
Also, something to keep in mind for the future, if a child is born on 31 December, their birth is probably going to be registered in the new year, and so will have a different registration year to their birth year.
T
You guys are awesome, at this stage I don't have any birth certs or birth transcriptions for Dorothy or Eric. As mentioned earlier I will get a transcription for Dorothy in the new year.
However I do have baptsims but they have confused me more
