I was trying to reconcile the summaries :-

1911 Summary

Name Number of Males Number of Females Street address Residence
Mr Blackmore 2 1 12 Station Road Aberystruth, Monmouthshire
Mr Blackmore 4 2 38 Glandwr Street Aberystruth, Monmouthshire
Mr Blackmore 3 2 29 Griffin Street Aberystruth, Monmouthshire
Mr Blackmore 2 2 2 Brynmorgan Ser Aberystruth, Monmouthshire
Mr Blackmore 2 5 4 Lower Pantypwdin Road Aberystruth, Monmouthshire
Mr Blackmore 1 1 Morris Lane Bedwellty, Monmouthshire
Mr Blackmore 2 2 4 Greenfield Terrace Tredegar, Monmouthshire
Mrs Blackmore 2 3 18 Woodfield Road Tredegar, Monmouthshire
Mr Blackmore 2 7 19 Harcourt Street Ebbw Vale, Monmouthshire
Mr Blackmore 6 3 26 Plantation Row Ebbw Vale, Monmouthshire
Mr Blackmore 3 2 2a Hart Street Ebbw Vale, Monmouthshire
Mr Blackmore 4 2 Park Farm Ebbw Vale, Monmouthshire
Mr Blackmore 1 1 32 Hall St Victoria Ebbw Vale, Monmouthshire
Mr Blackmore 3 3 122 Jubilee Road Bedwellty, Monmouthshire

with those at the same address as an ANNIE and LEWIS BLACKMORE

BLACKMORE ANNIE F 1884 27 Bedwellty Monmouthshire
BLACKMORE BEN M 1883 28 Bedwellty Monmouthshire
BLACKMORE BENJAMIN M 1847 64 Bedwellty Monmouthshire
BLACKMORE JOHN M 1888 23 Bedwellty Monmouthshire
BLACKMORE LEWIS M 1870 41 Bedwellty Monmouthshire

At that stage there may have been children, with hindsight as you say it may just be a couple , or some more adult Blackmores :-)