Depends on if the gifts to the other beneficiary's who have predeceased the testator also had the lapse language. They might well not have: it's more of a thing for the residual estate to avoid the whole intestacy thing.
The more I think about it the more I think it's possible that each beneficiary is being told "all the others agree".
Normally a will should ensure there is a residual beneficiary, which is where the lapse language comes in.
Unless specified otherwise, only those still alive on the testator's death can benefit from the will.
So if a will says to divide an estate equally between a, b and c, but c is dead, it is divided between a and b, unless the will states if c has already died to pass c's share to someone else, which I suspect is what the extract Nero posted is trying to say, but there wasn't enough of it to make it clear.
In the event of a car crash, and both occupants die, then it is deemed for the purpose of any will that the oldest died first.
I hope the solicitor has got good PI as the step daughter may have a case if there was an unreasonable time delay between instruction and signature, or the solicitor was aware that time was of the essence. Based on earlier comments I suspect it was a legal warehouse where the work was undertaken by a legal executive rather than a solicitor, which is why you see low fees quoted for certain types of legal work.