I looked up info about EC-1118 because of something I read in another thread, and found the Lallemand page:
Note that in section Oenological Properties, it reads: Competitive killer factor: yes
Folks have posted that some kits include packets of EC-1118 plus another yeast, with the intention that both are used. It appears that co-inoculating with EC-1118 is a waste of yeast, as it's likely to kill all competitors. If I purchased a kit with 2 yeasts, I'd not use the EC-1118 unless the ferment stuck.

Lalvin EC-1118™ | Lallemand Brewing
Lalvin EC-1118 is the perfect yeast for sparkling, fruity wines or to make cider. Ideal for low temperature fermentation and fast fermentation.
www.lallemandbrewing.com
Note that in section Oenological Properties, it reads: Competitive killer factor: yes
Folks have posted that some kits include packets of EC-1118 plus another yeast, with the intention that both are used. It appears that co-inoculating with EC-1118 is a waste of yeast, as it's likely to kill all competitors. If I purchased a kit with 2 yeasts, I'd not use the EC-1118 unless the ferment stuck.