Secondary sources disagree as to Jacob's parents.  I don't know who is correct.  And what is probably going on here is that these are not two different couples, but that the data on one couple is garbled.  In other words, John is Johann Peter and Catharine is Maria Christina Catharina.
Father:  John HAAS  (1745-1812)
Mother:  Catharine TREXLER
or
Father:  Johann Peter HAAS III (1748-1834)
Mother:  Maria Christina TREXLER (1753-1829)

1.  Clarence E. Beckel.  1912.  "Register of Marriages and Burials between the Years 1790 and 1810:  by the Rev. Johannes Heinrich Helffrich."  Pennsylvania Genealogical Magazine 5: 6-23 (reprinted 1983 as pp. 444-461 in Pennsylvania Vital Records.  Vol. II.  Genealogical Publ. Co., Baltimore, MD; issued 1997 as Broderbund CD-172).

p. 444	ABBREVIATIONS Mgschy. und Mcschy.—Macungie, Lehigh Co.
p. 451	1808 13 Dec. Mcshy. Jacob Haas et Catharina Kopp.

2.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

Jacob HAAS Birth: 10 Aug 1780, Lehigh, Pennsylvania Death: 26 Jul 1852 Father: Johann Peter HAAS III; Mother: Maria Christina TREXLER Marriage: 13 Dec 1803, Upper Macungie Twp, Lehigh, Pennsylvania Spouse: Catharine KOP Birth: 30 Aug 1780, Of Upper Macungie Twp, Lehigh, Pennsylvania Death: 02 Mar 1859 Child: Johann Peter HAAS, b. 20 Apr 1819, Upper Macungie Twp, Lehigh, Pennsylvania Child: Johann Philp HAAS, b. 20 Apr 1819, Upper Macungie Twp, Lehigh, Pennsylvania Source: patron submission

The birth/death dates for Jacob & Catharine presumably came from tombstones.  The death dates may be affected by some age-inflation because the 1810 census shows them born later (i.e., younger).

3.  1810 Census Index/Images (online at Ancestry.com; Image #1 of 2 in the "Bethlehem and Lower Nazereth" group; extracted by Diana Gale Matthiesen):¤•

1810

PA

Northampton Co.

Bethlehem Twp.

p. 77

Ln. 43

Jacob Haas

10100-00100-00

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	9 or under	1800-1810	= Jacob Jr. (b. 1805)
1 male	16-25	1784-1794	= Jacob
1 female	16-25	1784-1794	= Catharina

4.  1820 Census Index/Images (online at Ancestry.com; Image #2 of 6; extracted by Diana Gale Matthiesen):¤•

1820

PA

Northampton Co.

Bethlehem Twp.

p. 210A

Ln. 26

Haas Jacob

300010-20010-0-101

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
3 males	9 or under	1810-1820	= Philip (b. 1819) = Peter (b. 1819) = John (b. 1812)
1 male	26-44	1775-1794	= Jacob
2 females	9 or under	1810-1820	= Daughter A = Catharine (b. 1813)
1 female	26-44	1775-1794	= Catharina
1	person engaged in agriculture
1	person engaged in manufacture

Where's Jacob Jr?  Is he living/working out of the home?

5.  1830 Census Index/Images (online at Ancestry.com; Image #31 of 38; extracted by Diana Gale Matthiesen):¤•

1830

PA

Lehigh Co.

Macungie Twp.

Roll 155

p. 73

Ln. 11

Jacob Haas

013 020 100 - 010 100 100

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	5-9	1820-1825	= Son A
3 males	10-14	1815-1820	= Philip (b. 1819) = Peter (b. 1819) = John (b. 1812)
2 males	20-29	1800-1810	= Jacob Jr. (b. 1805) = ?
1 male	40-49	1780-1790	= Jacob
1 female	5-9	1820-1825	= Daughter B
1 female	15-19	1810-1815	= Catharine (b. 1813)
1 female	40-49	1780-1790	= Catharina

6.  1840 Census Index/Images (online at Ancestry.com; Image #1-2 of 20; extracted by Diana Gale Matthiesen):¤•

1840

PA

Lehigh Co.

Upper Macungie Twp.

Roll 469

pp. 195B-196A

Ln. 28

Jacob Haas

001 030 001 - 000 111 010

0300000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	10-14	1825-1830	= Son B
3 males	20-29	1810-1820	= Philip (b. 1819) = Peter (b. 1819) = John (b. 1812)
1 male	60-69	1770-1780	= Jacob
1 female	15-19	1820-1825	= Daughter C
1 female	20-29	1810-1820	= Catharine (b. 1813)
1 female	30-39	1800-1810	= ?
1 female	50-59	1780-1790	= Catharina
3	person employed in agriculture

Listed two lines above son, Jacob HAAS, Jr. (Ln. 30, 100001-10001 | 0001000).

7.  1850 Census Index/Images (online at Ancestry.com; Image #4 of 48):  Upper Macungie Twp., Lehigh Co., PA, Roll 792, p. 88B, 327/345, enumerated 26 Aug 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Jacob Haas	70	M		None	7000	Pennsylvania
Catharine	68	F				"
Anjuline Smith	19	F				"

Angeline is probably just hired help, but may be a granddaughter.  We may be experiencing some age inflation here.  Listed next to son, Jacob HAAS, Jr. (æ 45, wife Elisabeth), who is listed two households from son, Peter HAAS (æ 31, wife Judith).

8.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).