Lansweeper currently does not support multiple global credentials of the same type.
It is recommended to use more specific non-global credential mappings where possible. Global credentials will be used to interrogate with all detected assets of its type. Global credentials are only used if no other credentials are available, i.e. they have the lowest priority in the mapping order. The main intent of global credentials is to get customers on their way during the early setup phase. More specific credential mappings of non-global credentials should be implemented afterwards to ensure only the right credential is used for the right asset, rather than cycling credentials until the correct one is found.
Most environments will not have a "one credential fits all", as such in most cases having multiple global credentials will lead to a lot of, for instance, SSH authentication failure alerts if you're monitoring for this.