Yes, you can add multiple links to a channel within a campaign. We see many customers using this to better understand marketing efforts across a campaign lifecycle.
You can add up to 100 links to a channel within a single campaign. This is also the max number of links you can have in one campaign.
To add additional links to a specific channel within a Campaign select the channel under the campaign and select "Add Links"
From here you can paste in the long URL you wanted added to this channel and select 'Create' at the bottom.