You have 4 options:
1. To wait 3 months till visa is expired
2. To ask your first employer to cancel your visa, but they won't do it, because it is costly
3. To enter Qatar under your business visa, to stay here 1 day, and exit Qatar. Like if the visa was used, and no longer valid
4. To enter Qatar under your BV, and ask your first employer for NOC, so that your second employer could apply for your work visa while you are in Qatar, without exiting the country.
You have 4 options:
1. To wait 3 months till visa is expired
2. To ask your first employer to cancel your visa, but they won't do it, because it is costly
3. To enter Qatar under your business visa, to stay here 1 day, and exit Qatar. Like if the visa was used, and no longer valid
4. To enter Qatar under your BV, and ask your first employer for NOC, so that your second employer could apply for your work visa while you are in Qatar, without exiting the country.