I have two and need to keep them.
We had SIX BT telephone lines/numbers to the house originally from the 1990s - work and home landlines (still have those), fax line number (no longer have that), burglar alarm line (no longer have that) and a line into my older son's top floor room as he was the first to move from dial up to normal internet back in the day so that line is one of our broadband lines.
Today I have 3 numbers./ lines - (i) a work landline, given all the home working these days due to covid 19 ( used all the time for work calls - a nice static landline, corded, no digital display - perfect) which has full "fibre" (i.e. overhead copper wires from the Openreach box a distance away) broadband which is about £92 a month including the landline number (ii) the son's line mentioned above - doesn't do telephone calls but has the second broadband to house/ modem on it and (iii) the home telephone line - just used for telephone calls (i and ii are another 92 a month).
Mobile signal is not very good in this bit of outer London by the way (not even outer Hebrides but outer London). My son and I also organised raising about £12k about over a decade ago from neighbours to get the right kind of power to the nearest BT box thing and Openreach paid the other 2/3rds so that we could get internet fast enough to watch TV on.
I have two BT accounts using my 2 separate email addresses and two separate monthly bills with a broadband account on each (and a working landline telephone number on each). One reason I like to keep them is homeworking - two of my sons who live here work from home 2 days a week now due to covid rule changes and sometimes even more people are working from home, a son's friend who might be staying the night, my daughter, and we have a big house (2 boilers etc).
The only way ( even after trying boosters of many kinds) we can get the internet signal right over the other side of the house has been having one modem in my home office downstairs and the other 2 flights up at the other side. So it is because of obtaining signal in more rooms (even with that one son moved upstairs to work last week because of one downstairs room right the other side still with poor signal despite my paying BT about £92 x 2 a month.
The other reason is so we have one line if the other goes down. I am prepared to pay 92 to have the backup.
My sons did very important university and then post grad exams online all from here for 2.5 years until last year. The rules about observed/proctored (webcam) examinations done from home were thorough and very strict about if the line cuts out and what to do (our line was cutting out at least once a day at that point - both broadband lines but thankfully only briefly once cut out in an exam) . I just cannot risk having no internet and paying an extra 92 a month to have the second line is worth it for peace of mind (particularly with loss of landlines in power cuts with digital voice on the horizon in a poor mobile area).
The lines do often cut out for a short time once a day, sometimes more, TV pauses, bosses at work get cross. In fact one of my adult daugthers who had been "working from home" from my house (larger than her flat which also has a baby in it.....) twice a week decided not to do so any more due to her constant Teams calls here cutting out in that particular downstairs spare room (dining room with huge lovely to work at table) (the worst room for signal here).
At least my landlines always work and never stop (until Digital Voice will force the poorer service there on to us once it ceases to be "paused").
Anyway, short answer is with different email addresses and having had the two broadband lines/accounts since the 1990s I think it is I DO have two lines at the same property. It would be disastrous if BT were ever to remove them from me. If I ever get this house to myself and all the adult children go then I might well feel I can risk going down just to the one account.
