Lonely Sticky

By default, the plugin allows to have only one sticky post at a time, which
means that when saving a post that has been flagged as sticky, it automatically
unsticks other posts.

Under Settings > Lonely Sticky, an option can be found that allows you to
define how many sticky posts can exist at a time. For example, if a maximum of
3 posts is allowed, when saving a post that has been flagged as sticky, the two
most recent sticky posts present (if any) will be kept as sticky, along the one
that’s being saved.

Setting the option to 0 will disable sticky posts completely.