As per RFC 7208, multiple SPF records should not be added to DNS as SPF check will fail returning a "PermError".
This in turn may affect deliverability and your emails may be rejected by the receiver if your DMARC policy is set to reject.
For example, if you have two SPF records in DNS such as:
v=spf1 include:spf.protection.outlook.com -all
v=spf1 include:servers.mcsv.net -all
This will return PermError and both of the records need to be combined into one such as:
v=spf1 include:spf.protection.outlook.com include:servers.mcsv.net -all