@JayBeeW-
Unless you have very slow internet service from your internet provider (under 50 Mbps or so) you should have plenty to split between two video streams and still have enough left over for other uses (emails, browsing, etc).
Netflix-recommended internet download speeds PER STREAM:
Standard definition (SD):
1 Mbps
Note: A faster connection for improved video quality is recommended
High definition (HD)
720p: 3 Mbps
1080p: 5 Mbps
4K Ultra HD (UHD):
15 Mbps
Source: https://help.netflix.com/en/node/306
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