The state of Texas will not issue a driver license and a state identification card simultaneously. It also forbids carrying multiple in-state license/IDs, recommending destruction of the prior card after receipt of a new/renewed card. However, I still have a state identification card issued by another US state. Is it legal to carry the out-of-state ID card alongside a form of Texas identification?
Federal Code of Regulations (37.29) Prohibits holding more than one REAL ID card or more than one driver's license:
(a) An individual may hold only one REAL ID card. An individual cannot hold a REAL ID driver’s license and a REAL ID identification card simultaneously. Nothing shall preclude an individual from holding a REAL ID card and a non-REAL ID card unless prohibited by his or her State.
If the out-of-state identification card is REAL ID compliant then it is illegal at the Federal level to hold both that ID card and a REAL ID compliant driver's license.
The State of Texas has been producing REAL ID compliant driver's licenses since 2016.
The State of Texas is required, when issuing a REAL ID compliant driver's license, to check if the recipient holds a REAL ID card issued by another state. If so, then Texas is required to take steps to confirm that the ID card from the other state has been, or is being, terminated.
Section 521.009 of the Texas Transportation Code defines two types of certificates: election identification certificate and personal identification certificate.
Under Section 521.451, it is a general violation to possess more than one driver's license OR more than one valid certificate.
Section 521.183 states that a person only has to surrender identification certificates issued by Texas in order to get a driver's license.
This would seem to imply that it is not necessary to surrender, under Texas law, an ID card issued by another state in order to get a Texas driver's license.
Some states, such as California, issue both REAL ID compliant and non-compliant driver licenses and ID cards. The recipient decides which type of card is issued.
From the Department of Homeland Security FAQ regarding non-citizens:
REAL ID allows compliant states to issue driver's licenses and identification cards where the identity of the applicant cannot be assured or for whom lawful presence is not determined. In fact, some states currently issue such noncompliant cards to undocumented individuals. These cards must clearly state on their face (and in the machine readable zone) that it is not acceptable for official purposes and must use a unique design or color to differentiate them from compliant cards. DHS cautions against assuming that possession of a noncompliant card indicates the holder is an undocumented individual, given that several states issue noncompliant licenses for reasons unrelated to lawful presence.
In response to the link in the comment to subsection 3 of http://codes.findlaw.com/tx/transportation-code/transp-sect-521-451.html, that says
display or represent as the person's own a driver's license or certificate not issued to the person
This doesn't seem to apply to the question. However subsection 4 states:
possess more than one currently valid driver's license or more than one currently valid certificate
Assuming "certificate" means ID card, then it seems to clearly say you can have one of each. If Certificate is not an ID, then there is nothing specifically stating you can't have both.