@Sneha can you provide any screenshot examples of how you were initially envisioning using the bell icon in multiple places?

After some research, here are my initial findings:

• Overall, the assumptions here are correct—the bell icon refers to the same idea and cognitively should be perceived correctly, based on context, other apps do use the concepts of subscribing and notifications together, these actions are reversible so it's not a big deal.
• The main concern here would be the law of proximity, especially on mobile where the labels are dropping and you have the same icon relatively close to one another.
• A general finding from Neilson Norman Group is that digital icons get misinterpreted more commonly than we would like to think. This is why we should use icons as decorative elements which ideally accompany a label. That being said, the bell icon and the concept of subscribing and notifications is a very common and familiar one, so I'm not sure there would really be problems with this.
• YouTube for example, uses a bell icon for global notifications in the top header, while it explicitly spells out "subscribe" on videos. Slack, on the other hand, uses a bell icon to represent "Activity" as well "muting", and in the same overall interface. On the desktop app, you'll see these icons represented in various ways in the same interface, but not without either a label or tooltip explaining the action. On the mobile app, you won't necessarily find the bell icon representing various actions in the same interface.

My general recommendation would be that it is OK to use the bell icon to represent notifications in the header and subscribing to something within a page. I would suggest using a label wherever possible, particularly for subscribe, as that's a slightly less familiar action than a global notification bell. On mobile, where space is limited, consider where the two bells are located on the same page, or where something could be within a menu and ideally with a label. It is certainly worth learning from users either during a user test beforehand or from usage data afterwards to determine if there is any confusion and generally how these two concepts are translating through the bell icon.