My home has hail damage on 2 sides. Te siding is no longer made. Is the Ins. Co. required to make ALL the siding match?

I am not admitted in Iowa.  You need to read your policy.  What does it say as to replacement of the damaged area? 

There are multiple forms of Iowa homeowner's insurance, however the three most common forms are known as basic, broad and special.

Basic:  Protects your dwelling from 11 basic perils such as fire, lightning, wind, hail and theft.

Broad:  Protects your dwelling from the basic 11 perils plus six more. Additional perils include weight of snow or ice, collapse of structure and damage from household appliances.

Special:  Protects your home from all perils, except for damage or loss caused by flood or earthquake.

The most common type of coverage is the HO-3 policy, which pays for structural damage on a replacement cost basis. "Replacement" does not necessarily mean exact match so you may be out of luck.  There are policies knows as "restoration" policies - like those used in older buildings to restore plaster walls or decoration, etc. - but they are not standard and the premiums are very expensive.  See if your policy has "resotation" language.  Ask the agent to tell you "why" in writing.  Then you have a starting point.  Good luck.