A HELOC (Home Equity Line of Credit) is a revolving credit line that uses the realty property as collateral. This means if the consumer defaults on the credit line, the card issuer can take possession of the house. Obviously, only one lien can be placed on the property, therefore only one HELOC can be provided for that property. If the consumer wants 2 HELOCs, they will need 2 properties. In most likely the case, the issuer will provide a card that would be tied to the HELOC.
If the consumer wants a loan with their home as collateral, then they will need to apply for another mortgage. The new mortgage will be enough to cover the current mortgage + whatever extra the consumer will need. This assures that the home owner only has 1 mortgage.