Which urn material has a sturdy divider to avoid mixing ashes?

My husband and I have been together for 20 years, and we have been making pre-arrangements for when we pass on. We’ve both chosen to be cremated, but I also wanted to be buried, so my husband agreed to the compromise. Since I am Catholic, my remains are not to be divided or mixed with those of my dear husband, which makes me a bit sad because he really wanted them to commingle our ashes before final rest.